diff --git a/.gitea/workflows/deploy-questions.yml b/.gitea/workflows/deploy-questions.yml
index b2290a9..1bd44d1 100644
--- a/.gitea/workflows/deploy-questions.yml
+++ b/.gitea/workflows/deploy-questions.yml
@@ -79,6 +79,18 @@ jobs:
             --from-literal=purge-secret="$INTERNAL_PURGE_SECRET" \
             --dry-run=client -o yaml | kubectl apply -n step3-questions -f -
 
+      - name: Configure Stripe secrets
+        env:
+          STRIPE_SECRET_KEY: ${{ secrets.STRIPE_SECRET_KEY }}
+          STRIPE_WEBHOOK_SECRET: ${{ secrets.STRIPE_WEBHOOK_SECRET }}
+        run: |
+          test -n "$STRIPE_SECRET_KEY"
+          test -n "$STRIPE_WEBHOOK_SECRET"
+          kubectl create secret generic medmind-stripe \
+            --from-literal=secret-key="$STRIPE_SECRET_KEY" \
+            --from-literal=webhook-secret="$STRIPE_WEBHOOK_SECRET" \
+            --dry-run=client -o yaml | kubectl apply -n step3-questions -f -
+
       - name: Apply Questions deployment & service
         run: |
           kubectl apply -f api/QuestionsApi/k8s/deployment.yaml -n step3-questions
diff --git a/api/QuestionsApi.Tests/DonationTests.cs b/api/QuestionsApi.Tests/DonationTests.cs
new file mode 100644
index 0000000..20ceebc
--- /dev/null
+++ b/api/QuestionsApi.Tests/DonationTests.cs
@@ -0,0 +1,28 @@
+using QuestionsApi.Models;
+using Xunit;
+
+namespace QuestionsApi.Tests;
+
+public sealed class DonationTests
+{
+    [Theory]
+    [InlineData(499)]
+    [InlineData(1_000_001)]
+    public void RejectsAmountsOutsideConfiguredRange(long amountCents) =>
+        Assert.NotNull(DonationValidator.ValidateAmount(amountCents));
+
+    [Theory]
+    [InlineData(500)]
+    [InlineData(1_000)]
+    [InlineData(1_000_000)]
+    public void AcceptsAmountsInsideConfiguredRange(long amountCents) =>
+        Assert.Null(DonationValidator.ValidateAmount(amountCents));
+
+    [Fact]
+    public void PublicStatusDoesNotExposeStripeOrUserIdentifiers()
+    {
+        Assert.Null(typeof(DonationStatusResponse).GetProperty(nameof(Donation.UserId)));
+        Assert.Null(typeof(DonationStatusResponse).GetProperty(nameof(Donation.StripeCheckoutSessionId)));
+        Assert.Null(typeof(DonationStatusResponse).GetProperty(nameof(Donation.StripePaymentIntentId)));
+    }
+}
diff --git a/api/QuestionsApi/Controllers/DonationsController.cs b/api/QuestionsApi/Controllers/DonationsController.cs
new file mode 100644
index 0000000..5230381
--- /dev/null
+++ b/api/QuestionsApi/Controllers/DonationsController.cs
@@ -0,0 +1,86 @@
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using QuestionsApi.Models;
+using QuestionsApi.Services;
+using Stripe;
+using Stripe.Checkout;
+using System.Security.Claims;
+
+namespace QuestionsApi.Controllers;
+
+[ApiController, Route("api/donations")]
+public sealed class DonationsController(
+    DonationStore donations,
+    IStripeDonationGateway stripe,
+    IConfiguration configuration,
+    ILogger<DonationsController> logger) : ControllerBase
+{
+    [HttpPost("checkout"), Authorize(Roles = "USER,SUPER")]
+    public async Task<IActionResult> CreateCheckout(CreateDonationCheckoutRequest request, CancellationToken cancellationToken)
+    {
+        if (DonationValidator.ValidateAmount(request.AmountCents) is { } error) return BadRequest(error);
+        var donation = await donations.CreateAsync(UserId(), request.AmountCents);
+        try
+        {
+            var checkout = await stripe.CreateCheckoutAsync(donation.Id!, donation.AmountCents, cancellationToken);
+            await donations.AttachCheckoutSessionAsync(donation.Id!, checkout.SessionId);
+            return StatusCode(StatusCodes.Status201Created, new DonationCheckoutResponse
+            {
+                DonationId = donation.Id!, CheckoutUrl = checkout.CheckoutUrl, AmountCents = donation.AmountCents
+            });
+        }
+        catch (Exception exception)
+        {
+            await donations.MarkCheckoutCreationFailedAsync(donation.Id!, exception is StripeException ? "stripe_error" : "configuration_error");
+            logger.LogError(exception, "Unable to create Stripe Checkout Session for donation {DonationId}", donation.Id);
+            return Problem(statusCode: StatusCodes.Status502BadGateway, title: "Donation checkout unavailable",
+                detail: "The secure checkout could not be started. Please try again.");
+        }
+    }
+
+    [HttpGet("{id}"), Authorize(Roles = "USER,SUPER")]
+    public async Task<IActionResult> GetStatus(string id) =>
+        await donations.GetOwnedAsync(id.Trim(), UserId()) is { } donation
+            ? Ok(DonationStatusResponse.FromModel(donation))
+            : NotFound();
+
+    [HttpPost("stripe-webhook"), AllowAnonymous]
+    public async Task<IActionResult> StripeWebhook(CancellationToken cancellationToken)
+    {
+        var webhookSecret = configuration["Stripe:WebhookSecret"];
+        if (string.IsNullOrWhiteSpace(webhookSecret)) return Problem(statusCode: 503, title: "Stripe webhook is not configured");
+        using var reader = new StreamReader(Request.Body);
+        var json = await reader.ReadToEndAsync(cancellationToken);
+        Event stripeEvent;
+        try
+        {
+            stripeEvent = EventUtility.ConstructEvent(json, Request.Headers["Stripe-Signature"], webhookSecret);
+        }
+        catch (StripeException exception)
+        {
+            logger.LogWarning(exception, "Rejected Stripe webhook with an invalid signature");
+            return BadRequest("Invalid Stripe signature");
+        }
+
+        if (stripeEvent.Data.Object is not Session session) return Ok();
+        var status = stripeEvent.Type switch
+        {
+            "checkout.session.completed" when session.PaymentStatus == "paid" => DonationStatus.Paid,
+            "checkout.session.async_payment_succeeded" => DonationStatus.Paid,
+            "checkout.session.async_payment_failed" => DonationStatus.Failed,
+            "checkout.session.expired" => DonationStatus.Expired,
+            _ => ""
+        };
+        if (status.Length == 0) return Ok();
+        var donationId = session.ClientReferenceId;
+        if (string.IsNullOrWhiteSpace(donationId) && session.Metadata.TryGetValue("donation_id", out var metadataId)) donationId = metadataId;
+        var applied = await donations.ApplyStripeStatusAsync(
+            donationId ?? "", session.Id, session.AmountTotal ?? 0, session.Currency ?? "",
+            status, session.PaymentIntentId ?? "", stripeEvent.Id);
+        if (!applied) logger.LogWarning("Stripe event {EventId} did not match donation {DonationId}", stripeEvent.Id, donationId);
+        return Ok();
+    }
+
+    private string UserId() => User.FindFirstValue(ClaimTypes.NameIdentifier)
+        ?? User.FindFirstValue(ClaimTypes.Name) ?? User.Identity?.Name ?? "";
+}
diff --git a/api/QuestionsApi/Models/Donation.cs b/api/QuestionsApi/Models/Donation.cs
new file mode 100644
index 0000000..4cf9bb5
--- /dev/null
+++ b/api/QuestionsApi/Models/Donation.cs
@@ -0,0 +1,75 @@
+using MongoDB.Bson;
+using MongoDB.Bson.Serialization.Attributes;
+
+namespace QuestionsApi.Models;
+
+public static class DonationStatus
+{
+    public const string Pending = "pending";
+    public const string Paid = "paid";
+    public const string Failed = "failed";
+    public const string Expired = "expired";
+}
+
+public sealed class Donation
+{
+    [BsonId, BsonRepresentation(BsonType.ObjectId)] public string? Id { get; set; }
+    public string UserId { get; set; } = "";
+    public long AmountCents { get; set; }
+    public string Currency { get; set; } = "usd";
+    public string Status { get; set; } = DonationStatus.Pending;
+    [BsonIgnoreIfNull] public string? StripeCheckoutSessionId { get; set; }
+    public string StripePaymentIntentId { get; set; } = "";
+    public string LastStripeEventId { get; set; } = "";
+    public string FailureCode { get; set; } = "";
+    public DateTime CreatedUtc { get; set; } = DateTime.UtcNow;
+    public DateTime UpdatedUtc { get; set; } = DateTime.UtcNow;
+    public DateTime? PaidUtc { get; set; }
+}
+
+public sealed class CreateDonationCheckoutRequest
+{
+    public long AmountCents { get; set; }
+}
+
+public sealed class DonationCheckoutResponse
+{
+    public string DonationId { get; set; } = "";
+    public string CheckoutUrl { get; set; } = "";
+    public long AmountCents { get; set; }
+    public string Currency { get; set; } = "usd";
+    public string Status { get; set; } = DonationStatus.Pending;
+}
+
+public sealed class DonationStatusResponse
+{
+    public string DonationId { get; set; } = "";
+    public long AmountCents { get; set; }
+    public string Currency { get; set; } = "usd";
+    public string Status { get; set; } = DonationStatus.Pending;
+    public DateTime CreatedUtc { get; set; }
+    public DateTime? PaidUtc { get; set; }
+
+    public static DonationStatusResponse FromModel(Donation donation) => new()
+    {
+        DonationId = donation.Id ?? "",
+        AmountCents = donation.AmountCents,
+        Currency = donation.Currency,
+        Status = donation.Status,
+        CreatedUtc = donation.CreatedUtc,
+        PaidUtc = donation.PaidUtc
+    };
+}
+
+public static class DonationValidator
+{
+    public const long MinimumAmountCents = 500;
+    public const long MaximumAmountCents = 1_000_000;
+
+    public static string? ValidateAmount(long amountCents) => amountCents switch
+    {
+        < MinimumAmountCents => "amountCents must be at least 500",
+        > MaximumAmountCents => "amountCents must be no more than 1000000",
+        _ => null
+    };
+}
diff --git a/api/QuestionsApi/Program.cs b/api/QuestionsApi/Program.cs
index 7e52ca3..b9d6c5b 100644
--- a/api/QuestionsApi/Program.cs
+++ b/api/QuestionsApi/Program.cs
@@ -26,6 +26,8 @@ builder.Services.AddSingleton<QuestionBookmarkStore>();
 builder.Services.AddSingleton<ReviewQueueStore>();
 builder.Services.AddSingleton<DashboardStore>();
 builder.Services.AddSingleton<UserProfileStore>();
+builder.Services.AddSingleton<DonationStore>();
+builder.Services.AddSingleton<IStripeDonationGateway, StripeDonationGateway>();
 builder.Services.AddSingleton<ServiceMetrics>();
 builder.Services.AddHostedService<AnswerStatisticsMaintenanceService>();
 
diff --git a/api/QuestionsApi/QuestionsApi.csproj b/api/QuestionsApi/QuestionsApi.csproj
index 0cb0950..8f1c9dd 100644
--- a/api/QuestionsApi/QuestionsApi.csproj
+++ b/api/QuestionsApi/QuestionsApi.csproj
@@ -10,6 +10,7 @@
     <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="8.0.8" />
     <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.8" />
     <PackageReference Include="MongoDB.Driver" Version="3.4.3" />
+    <PackageReference Include="Stripe.net" Version="52.1.1" />
     <PackageReference Include="Swashbuckle.AspNetCore" Version="6.5.0" />
   </ItemGroup>
 
diff --git a/api/QuestionsApi/Services/DonationStore.cs b/api/QuestionsApi/Services/DonationStore.cs
new file mode 100644
index 0000000..50d2100
--- /dev/null
+++ b/api/QuestionsApi/Services/DonationStore.cs
@@ -0,0 +1,74 @@
+using MongoDB.Driver;
+using QuestionsApi.Models;
+
+namespace QuestionsApi.Services;
+
+public sealed class DonationStore
+{
+    private readonly IMongoCollection<Donation> _donations;
+
+    public DonationStore(MongoDatabaseProvider mongo)
+    {
+        _donations = mongo.Database.GetCollection<Donation>("Donations");
+        _donations.Indexes.CreateMany([
+            new CreateIndexModel<Donation>(Builders<Donation>.IndexKeys.Ascending(value => value.UserId).Descending(value => value.CreatedUtc)),
+            new CreateIndexModel<Donation>(Builders<Donation>.IndexKeys.Ascending(value => value.StripeCheckoutSessionId),
+                new CreateIndexOptions<Donation>
+                {
+                    Unique = true,
+                    PartialFilterExpression = Builders<Donation>.Filter.Type(value => value.StripeCheckoutSessionId, MongoDB.Bson.BsonType.String)
+                }),
+            new CreateIndexModel<Donation>(Builders<Donation>.IndexKeys.Ascending(value => value.Status).Descending(value => value.CreatedUtc))
+        ]);
+    }
+
+    public async Task<Donation> CreateAsync(string userId, long amountCents)
+    {
+        var donation = new Donation { UserId = userId, AmountCents = amountCents };
+        await _donations.InsertOneAsync(donation);
+        return donation;
+    }
+
+    public async Task<Donation?> GetOwnedAsync(string id, string userId) =>
+        await _donations.Find(value => value.Id == id && value.UserId == userId).FirstOrDefaultAsync();
+
+    public async Task AttachCheckoutSessionAsync(string id, string sessionId) =>
+        await _donations.UpdateOneAsync(
+            value => value.Id == id && value.Status == DonationStatus.Pending,
+            Builders<Donation>.Update.Set(value => value.StripeCheckoutSessionId, sessionId).Set(value => value.UpdatedUtc, DateTime.UtcNow));
+
+    public async Task MarkCheckoutCreationFailedAsync(string id, string failureCode) =>
+        await _donations.UpdateOneAsync(
+            value => value.Id == id && value.Status == DonationStatus.Pending,
+            Builders<Donation>.Update.Set(value => value.Status, DonationStatus.Failed)
+                .Set(value => value.FailureCode, failureCode).Set(value => value.UpdatedUtc, DateTime.UtcNow));
+
+    public async Task<bool> ApplyStripeStatusAsync(
+        string id,
+        string sessionId,
+        long amountCents,
+        string currency,
+        string status,
+        string paymentIntentId,
+        string eventId)
+    {
+        if (string.IsNullOrWhiteSpace(id) || string.IsNullOrWhiteSpace(sessionId)) return false;
+        var filter = Builders<Donation>.Filter.Eq(value => value.Id, id)
+            & Builders<Donation>.Filter.Eq(value => value.AmountCents, amountCents)
+            & Builders<Donation>.Filter.Eq(value => value.Currency, currency.ToLowerInvariant())
+            & (Builders<Donation>.Filter.Eq(value => value.StripeCheckoutSessionId, sessionId)
+                | Builders<Donation>.Filter.Eq(value => value.StripeCheckoutSessionId, null));
+
+        if (status != DonationStatus.Paid)
+            filter &= Builders<Donation>.Filter.Eq(value => value.Status, DonationStatus.Pending);
+
+        var now = DateTime.UtcNow;
+        var update = Builders<Donation>.Update.Set(value => value.Status, status)
+            .Set(value => value.StripeCheckoutSessionId, sessionId)
+            .Set(value => value.StripePaymentIntentId, paymentIntentId)
+            .Set(value => value.LastStripeEventId, eventId)
+            .Set(value => value.UpdatedUtc, now);
+        if (status == DonationStatus.Paid) update = update.Set(value => value.PaidUtc, now);
+        return (await _donations.UpdateOneAsync(filter, update)).ModifiedCount > 0;
+    }
+}
diff --git a/api/QuestionsApi/Services/StripeDonationGateway.cs b/api/QuestionsApi/Services/StripeDonationGateway.cs
new file mode 100644
index 0000000..4caf229
--- /dev/null
+++ b/api/QuestionsApi/Services/StripeDonationGateway.cs
@@ -0,0 +1,57 @@
+using Stripe;
+using Stripe.Checkout;
+
+namespace QuestionsApi.Services;
+
+public sealed record StripeCheckoutResult(string SessionId, string CheckoutUrl);
+
+public interface IStripeDonationGateway
+{
+    Task<StripeCheckoutResult> CreateCheckoutAsync(string donationId, long amountCents, CancellationToken cancellationToken);
+}
+
+public sealed class StripeDonationGateway(IConfiguration configuration) : IStripeDonationGateway
+{
+    public async Task<StripeCheckoutResult> CreateCheckoutAsync(string donationId, long amountCents, CancellationToken cancellationToken)
+    {
+        var secretKey = configuration["Stripe:SecretKey"];
+        if (string.IsNullOrWhiteSpace(secretKey)) throw new InvalidOperationException("Stripe secret key is not configured.");
+        var successUrl = configuration["Stripe:SuccessUrl"]
+            ?? "https://doctor.ranaze.com/donation-complete.html?session_id={CHECKOUT_SESSION_ID}";
+        var cancelUrl = configuration["Stripe:CancelUrl"] ?? "https://doctor.ranaze.com/donation-canceled.html";
+        var client = new StripeClient(secretKey);
+        var service = new SessionService(client);
+        var metadata = new Dictionary<string, string> { ["donation_id"] = donationId };
+        var session = await service.CreateAsync(new SessionCreateOptions
+        {
+            Mode = "payment",
+            SuccessUrl = successUrl,
+            CancelUrl = cancelUrl,
+            ClientReferenceId = donationId,
+            CustomerCreation = "always",
+            BillingAddressCollection = "auto",
+            Metadata = metadata,
+            PaymentIntentData = new SessionPaymentIntentDataOptions { Metadata = metadata },
+            LineItems =
+            [
+                new SessionLineItemOptions
+                {
+                    Quantity = 1,
+                    PriceData = new SessionLineItemPriceDataOptions
+                    {
+                        Currency = "usd",
+                        UnitAmount = amountCents,
+                        ProductData = new SessionLineItemPriceDataProductDataOptions
+                        {
+                            Name = "Support MedMind",
+                            Description = "One-time contribution supporting MedMind development and medical education content."
+                        }
+                    }
+                }
+            ]
+        }, null, cancellationToken);
+        if (string.IsNullOrWhiteSpace(session.Id) || string.IsNullOrWhiteSpace(session.Url))
+            throw new InvalidOperationException("Stripe did not return a checkout URL.");
+        return new StripeCheckoutResult(session.Id, session.Url);
+    }
+}
diff --git a/api/QuestionsApi/appsettings.Development.json b/api/QuestionsApi/appsettings.Development.json
index b6ce260..abeee2a 100644
--- a/api/QuestionsApi/appsettings.Development.json
+++ b/api/QuestionsApi/appsettings.Development.json
@@ -2,6 +2,10 @@
   "Kestrel": { "Endpoints": { "Http": { "Url": "http://0.0.0.0:5008" } } },
   "MongoDB": { "ConnectionString": "mongodb://192.168.86.50:27017", "DatabaseName": "promiscuity" },
   "AnswerStatistics": { "ReconcileSeconds": 300 },
+  "Stripe": {
+    "SuccessUrl": "https://doctor.ranaze.com/donation-complete.html?session_id={CHECKOUT_SESSION_ID}",
+    "CancelUrl": "https://doctor.ranaze.com/donation-canceled.html"
+  },
   "Jwt": { "Key": "SuperUltraSecureJwtKeyWithAtLeast32Chars!!", "Issuer": "promiscuity", "Audience": "promiscuity-auth-api" },
   "Logging": { "LogLevel": { "Default": "Information" } }
 }
diff --git a/api/QuestionsApi/appsettings.json b/api/QuestionsApi/appsettings.json
index 226f593..d4537a1 100644
--- a/api/QuestionsApi/appsettings.json
+++ b/api/QuestionsApi/appsettings.json
@@ -2,6 +2,10 @@
   "Kestrel": { "Endpoints": { "Http": { "Url": "http://0.0.0.0:5008" } } },
   "MongoDB": { "ConnectionString": "mongodb://192.168.86.50:27017", "DatabaseName": "promiscuity" },
   "AnswerStatistics": { "ReconcileSeconds": 300 },
+  "Stripe": {
+    "SuccessUrl": "https://doctor.ranaze.com/donation-complete.html?session_id={CHECKOUT_SESSION_ID}",
+    "CancelUrl": "https://doctor.ranaze.com/donation-canceled.html"
+  },
   "Jwt": { "Key": "SuperUltraSecureJwtKeyWithAtLeast32Chars!!", "Issuer": "promiscuity", "Audience": "promiscuity-auth-api" },
   "Logging": { "LogLevel": { "Default": "Information" } },
   "AllowedHosts": "*"
diff --git a/api/QuestionsApi/k8s/deployment.yaml b/api/QuestionsApi/k8s/deployment.yaml
index f5d7294..12767a6 100644
--- a/api/QuestionsApi/k8s/deployment.yaml
+++ b/api/QuestionsApi/k8s/deployment.yaml
@@ -35,6 +35,16 @@ spec:
                 secretKeyRef:
                   name: medmind-internal-api
                   key: purge-secret
+            - name: Stripe__SecretKey
+              valueFrom:
+                secretKeyRef:
+                  name: medmind-stripe
+                  key: secret-key
+            - name: Stripe__WebhookSecret
+              valueFrom:
+                secretKeyRef:
+                  name: medmind-stripe
+                  key: webhook-secret
           resources:
             requests:
               cpu: 250m
diff --git a/docs/STRIPE_DONATIONS.md b/docs/STRIPE_DONATIONS.md
new file mode 100644
index 0000000..2b8140a
--- /dev/null
+++ b/docs/STRIPE_DONATIONS.md
@@ -0,0 +1,56 @@
+# Stripe Donations
+
+MedMind accepts authenticated, one-time USD contributions through Stripe-hosted Checkout. The API enforces a minimum contribution of $5 and a maximum of $10,000. Payment card data never passes through or is stored by MedMind.
+
+Contributions are not tax-deductible.
+
+## Stripe test-mode setup
+
+1. In the Stripe Dashboard, switch to test mode.
+2. Create a webhook endpoint at:
+
+   `https://s3q.ranaze.com/api/donations/stripe-webhook`
+
+3. Subscribe the endpoint to these events:
+
+   - `checkout.session.completed`
+   - `checkout.session.async_payment_succeeded`
+   - `checkout.session.async_payment_failed`
+   - `checkout.session.expired`
+
+4. Copy the webhook signing secret (`whsec_...`).
+5. Copy a test secret API key (`sk_test_...`).
+6. Add both values as Gitea Actions secrets in the API repository:
+
+   - `STRIPE_SECRET_KEY`
+   - `STRIPE_WEBHOOK_SECRET`
+
+The deployment workflow writes these values to the Kubernetes secret `medmind-stripe`. Never commit either value to the repository.
+
+## Stripe account settings
+
+Configure MedMind branding in Stripe Checkout and enable successful-payment email receipts in Stripe customer email settings. Stripe Checkout collects the contributor's email address.
+
+## Verification
+
+After deployment:
+
+1. Sign in to MedMind and open **Support MedMind** from the sidebar.
+2. Confirm that amounts below $5 and above $10,000 are rejected.
+3. Start a $5 test contribution.
+4. Complete Checkout using Stripe's standard test card `4242 4242 4242 4242`, any future expiration date, and any CVC.
+5. Return to MedMind and confirm the contribution changes from pending to confirmed.
+6. In Stripe, confirm the Checkout Session and webhook delivery both succeeded.
+7. In MongoDB, confirm the corresponding `Donations` document has `Status: "paid"` and a populated `PaidUtc` value.
+
+The client-visible status endpoint returns only the donation ID, amount, currency, status, creation time, and paid time. Stripe payment identifiers and webhook metadata remain server-side.
+
+## Live-mode cutover
+
+1. Create the same webhook endpoint in Stripe live mode.
+2. Replace `STRIPE_SECRET_KEY` with the live secret key (`sk_live_...`).
+3. Replace `STRIPE_WEBHOOK_SECRET` with the live endpoint's signing secret.
+4. Trigger a deployment and complete a small real contribution.
+5. Confirm the payment, receipt, webhook delivery, and `paid` status before announcing availability.
+
+Test and live webhook signing secrets are different. Both Stripe secrets must always belong to the same Stripe mode.
diff --git a/project.godot b/project.godot
index b1d54b6..9fd353a 100644
--- a/project.godot
+++ b/project.godot
@@ -33,6 +33,7 @@ BookmarkService="*res://scripts/autoload/bookmark_service.gd"
 ReviewQueueService="*res://scripts/autoload/review_queue_service.gd"
 DashboardService="*res://scripts/autoload/dashboard_service.gd"
 AccountProfileService="*res://scripts/autoload/account_profile_service.gd"
+DonationService="*res://scripts/autoload/donation_service.gd"
 
 [display]
 
@@ -60,5 +61,6 @@ app_feedback_api_url="https://s3q.ranaze.com/api/app-feedback"
 notes_api_url="https://s3q.ranaze.com/api/notes"
 dashboard_api_url="https://s3q.ranaze.com/api/dashboard"
 profile_api_url="https://s3q.ranaze.com/api/profile"
+donations_api_url="https://s3q.ranaze.com/api/donations"
 review_queue_api_url="https://s3q.ranaze.com/api/review-queue"
 build_revision="development"
diff --git a/scripts/autoload/donation_service.gd b/scripts/autoload/donation_service.gd
new file mode 100644
index 0000000..08761f8
--- /dev/null
+++ b/scripts/autoload/donation_service.gd
@@ -0,0 +1,176 @@
+extends Node
+
+const EndpointConfig := preload("res://scripts/autoload/api_endpoint_config.gd")
+const DEFAULT_URL := "https://s3q.ranaze.com/api/donations"
+const REQUEST_TIMEOUT_SECONDS := 30.0
+const POLL_INTERVAL_SECONDS := 3.0
+const POLL_LIMIT := 200
+
+signal checkout_started(donation_id: String, checkout_url: String)
+signal donation_status_changed(status: String, donation: Dictionary)
+signal donation_failed(message: String)
+
+var api_url := DEFAULT_URL
+var checkout_request: HTTPRequest
+var status_request: HTTPRequest
+var poll_timer: Timer
+var request_token := ""
+var active_donation_id := ""
+var poll_count := 0
+var checkout_pending := false
+var status_pending := false
+
+
+func _ready() -> void:
+	api_url = EndpointConfig.resolve(
+		str(ProjectSettings.get_setting("step3/donations_api_url", DEFAULT_URL)),
+		"/api/donations")
+	checkout_request = HTTPRequest.new()
+	checkout_request.timeout = REQUEST_TIMEOUT_SECONDS
+	checkout_request.request_completed.connect(_on_checkout_completed)
+	add_child(checkout_request)
+	status_request = HTTPRequest.new()
+	status_request.timeout = REQUEST_TIMEOUT_SECONDS
+	status_request.request_completed.connect(_on_status_completed)
+	add_child(status_request)
+	poll_timer = Timer.new()
+	poll_timer.wait_time = POLL_INTERVAL_SECONDS
+	poll_timer.timeout.connect(_poll_status)
+	add_child(poll_timer)
+	AuthState.auth_changed.connect(_on_auth_changed)
+
+
+func begin_checkout(amount_cents: int) -> void:
+	if checkout_pending:
+		return
+	if not AuthState.can_send_authenticated_request():
+		donation_failed.emit("Log in before making a contribution.")
+		return
+	_prepare_browser_window()
+	checkout_pending = true
+	request_token = AuthState.access_token
+	var headers := PackedStringArray([
+		"Content-Type: application/json",
+		"Authorization: Bearer %s" % request_token
+	])
+	var error := checkout_request.request(
+		"%s/checkout" % api_url.rstrip("/"), headers, HTTPClient.METHOD_POST,
+		JSON.stringify({"amountCents": amount_cents}))
+	if error != OK:
+		checkout_pending = false
+		_close_browser_window()
+		donation_failed.emit("The secure checkout request could not be started.")
+
+
+func stop_polling() -> void:
+	poll_timer.stop()
+	poll_count = 0
+	if status_pending and status_request.get_http_client_status() != HTTPClient.STATUS_DISCONNECTED:
+		status_request.cancel_request()
+	status_pending = false
+
+
+func resume_polling() -> void:
+	if active_donation_id.is_empty() or poll_timer == null:
+		return
+	poll_timer.start()
+	_poll_status()
+
+
+func _on_checkout_completed(result: int, response_code: int, _headers: PackedStringArray, body: PackedByteArray) -> void:
+	checkout_pending = false
+	if response_code == 401:
+		AuthState.handle_unauthorized(request_token)
+	if result != HTTPRequest.RESULT_SUCCESS or response_code < 200 or response_code >= 300:
+		_close_browser_window()
+		donation_failed.emit(_failure_message("Checkout could not be started.", result, response_code, body))
+		return
+	var parsed: Variant = JSON.parse_string(body.get_string_from_utf8())
+	if typeof(parsed) != TYPE_DICTIONARY:
+		_close_browser_window()
+		donation_failed.emit("The donation service returned an invalid response.")
+		return
+	var donation_id := str(parsed.get("donationId", ""))
+	var checkout_url := str(parsed.get("checkoutUrl", ""))
+	if donation_id.is_empty() or not checkout_url.begins_with("https://"):
+		_close_browser_window()
+		donation_failed.emit("The donation service returned an invalid checkout link.")
+		return
+	active_donation_id = donation_id
+	_open_checkout_url(checkout_url)
+	checkout_started.emit(donation_id, checkout_url)
+	poll_count = 0
+	poll_timer.start()
+	_poll_status()
+
+
+func _poll_status() -> void:
+	if status_pending or active_donation_id.is_empty() or not AuthState.can_send_authenticated_request():
+		return
+	poll_count += 1
+	if poll_count > POLL_LIMIT:
+		stop_polling()
+		return
+	status_pending = true
+	request_token = AuthState.access_token
+	var headers := PackedStringArray(["Authorization: Bearer %s" % request_token])
+	var error := status_request.request("%s/%s" % [api_url.rstrip("/"), active_donation_id], headers)
+	if error != OK:
+		status_pending = false
+
+
+func _on_status_completed(result: int, response_code: int, _headers: PackedStringArray, body: PackedByteArray) -> void:
+	status_pending = false
+	if response_code == 401:
+		AuthState.handle_unauthorized(request_token)
+		stop_polling()
+		return
+	if result != HTTPRequest.RESULT_SUCCESS or response_code < 200 or response_code >= 300:
+		return
+	var parsed: Variant = JSON.parse_string(body.get_string_from_utf8())
+	if typeof(parsed) != TYPE_DICTIONARY:
+		return
+	var status := str(parsed.get("status", ""))
+	donation_status_changed.emit(status, parsed)
+	if status in ["paid", "failed", "expired"]:
+		stop_polling()
+
+
+func _prepare_browser_window() -> void:
+	if OS.has_feature("web"):
+		JavaScriptBridge.eval(
+			"window.medmindDonationWindow = window.open('about:blank', 'medmind_donation_checkout');",
+			true)
+
+
+func _open_checkout_url(url: String) -> void:
+	if OS.has_feature("web"):
+		JavaScriptBridge.eval(
+			"if (window.medmindDonationWindow && !window.medmindDonationWindow.closed) { window.medmindDonationWindow.location.href = %s; window.medmindDonationWindow.focus(); } else { window.open(%s, '_blank'); }" % [JSON.stringify(url), JSON.stringify(url)],
+			true)
+	else:
+		OS.shell_open(url)
+
+
+func _close_browser_window() -> void:
+	if OS.has_feature("web"):
+		JavaScriptBridge.eval(
+			"if (window.medmindDonationWindow && !window.medmindDonationWindow.closed) { window.medmindDonationWindow.close(); } window.medmindDonationWindow = null;",
+			true)
+
+
+func _failure_message(prefix: String, result: int, response_code: int, body: PackedByteArray) -> String:
+	if result != HTTPRequest.RESULT_SUCCESS and response_code == 0:
+		return "%s Check your connection and try again." % prefix
+	var parsed: Variant = JSON.parse_string(body.get_string_from_utf8())
+	if typeof(parsed) == TYPE_DICTIONARY:
+		var detail := str(parsed.get("detail", "")).strip_edges()
+		if not detail.is_empty():
+			return detail
+	return "%s Status %d." % [prefix, response_code]
+
+
+func _on_auth_changed() -> void:
+	if not AuthState.is_logged_in:
+		stop_polling()
+		active_donation_id = ""
diff --git a/scripts/autoload/donation_service.gd.uid b/scripts/autoload/donation_service.gd.uid
new file mode 100644
index 0000000..5fefc6e
--- /dev/null
+++ b/scripts/autoload/donation_service.gd.uid
@@ -0,0 +1 @@
+uid://b20e6ch7a4dtb
diff --git a/scripts/ui/donation_amount.gd b/scripts/ui/donation_amount.gd
new file mode 100644
index 0000000..aa813ba
--- /dev/null
+++ b/scripts/ui/donation_amount.gd
@@ -0,0 +1,18 @@
+extends RefCounted
+
+
+static func parse_cents(value: String) -> int:
+	var cleaned := value.strip_edges().trim_prefix("$").replace(",", "")
+	var matcher := RegEx.new()
+	matcher.compile("^[0-9]+(?:\\.[0-9]{1,2})?$")
+	if matcher.search(cleaned) == null:
+		return -1
+	var parts := cleaned.split(".")
+	var dollars := int(parts[0])
+	var cents := 0
+	if parts.size() == 2:
+		var fraction := str(parts[1])
+		cents = int(fraction) * (10 if fraction.length() == 1 else 1)
+	if dollars > 10000 or (dollars == 10000 and cents > 0):
+		return -1
+	return dollars * 100 + cents
diff --git a/scripts/ui/donation_amount.gd.uid b/scripts/ui/donation_amount.gd.uid
new file mode 100644
index 0000000..9fac093
--- /dev/null
+++ b/scripts/ui/donation_amount.gd.uid
@@ -0,0 +1 @@
+uid://2ha4l3mmlb61
diff --git a/scripts/ui/donation_screen.gd b/scripts/ui/donation_screen.gd
new file mode 100644
index 0000000..48de962
--- /dev/null
+++ b/scripts/ui/donation_screen.gd
@@ -0,0 +1,316 @@
+extends MarginContainer
+
+const Brand := preload("res://scripts/ui/medmind_style.gd")
+const Style := preload("res://scripts/ui/ui_style.gd")
+const DonationAmount := preload("res://scripts/ui/donation_amount.gd")
+const MINIMUM_CENTS := 500
+const MAXIMUM_CENTS := 1000000
+const DEFAULT_CENTS := 2500
+
+var main: Control
+var content_grid: GridContainer
+var mission_panel: PanelContainer
+var contribution_panel: PanelContainer
+var preset_grid: GridContainer
+var amount_buttons: Array[Button] = []
+var amount_group := ButtonGroup.new()
+var custom_amount: LineEdit
+var donate_button: Button
+var status_label: Label
+var selected_amount_cents := DEFAULT_CENTS
+var donation_service: Node
+
+
+func _ready() -> void:
+	donation_service = get_node("/root/DonationService")
+	set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
+	add_theme_constant_override("margin_bottom", 8)
+	_build_ui()
+	resized.connect(_update_layout)
+	donation_service.checkout_started.connect(_on_checkout_started)
+	donation_service.donation_status_changed.connect(_on_donation_status_changed)
+	donation_service.donation_failed.connect(_on_donation_failed)
+	UIThemeService.theme_changed.connect(_on_theme_changed)
+	_update_layout()
+	_update_donate_button()
+	refresh_theme_controls()
+
+
+func _build_ui() -> void:
+	var scroll := ScrollContainer.new()
+	scroll.size_flags_horizontal = Control.SIZE_EXPAND_FILL
+	scroll.size_flags_vertical = Control.SIZE_EXPAND_FILL
+	scroll.horizontal_scroll_mode = ScrollContainer.SCROLL_MODE_DISABLED
+	add_child(scroll)
+
+	var page := VBoxContainer.new()
+	page.custom_minimum_size = Vector2(0, 0)
+	page.size_flags_horizontal = Control.SIZE_EXPAND_FILL
+	page.add_theme_constant_override("separation", 24)
+	scroll.add_child(page)
+
+	var title := Label.new()
+	title.text = "Support MedMind"
+	title.add_theme_font_override("font", Brand.font)
+	title.add_theme_font_size_override("font_size", 36)
+	page.add_child(title)
+
+	var subtitle := Label.new()
+	subtitle.text = "Help us build accessible, clinically grounded tools for Step 3 learners."
+	subtitle.add_theme_font_override("font", Brand.font)
+	subtitle.add_theme_font_size_override("font_size", 18)
+	subtitle.add_theme_color_override("font_color", Brand.muted_color(UIThemeService.is_dark_mode()))
+	subtitle.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
+	page.add_child(subtitle)
+
+	content_grid = GridContainer.new()
+	content_grid.columns = 2
+	content_grid.size_flags_horizontal = Control.SIZE_EXPAND_FILL
+	content_grid.add_theme_constant_override("h_separation", 24)
+	content_grid.add_theme_constant_override("v_separation", 24)
+	page.add_child(content_grid)
+
+	mission_panel = _panel()
+	mission_panel.size_flags_horizontal = Control.SIZE_EXPAND_FILL
+	content_grid.add_child(mission_panel)
+	var mission := VBoxContainer.new()
+	mission.add_theme_constant_override("separation", 18)
+	mission_panel.add_child(mission)
+	mission.add_child(_heading("Our mission", 26))
+	mission.add_child(_body("MedMind exists to make rigorous, clinically grounded medical education more accessible. We are building an independent Step 3 study experience that helps learners develop clinical judgment through original questions, realistic CCS cases, transparent explanations, and continuous improvement driven by learner feedback."))
+	mission.add_child(HSeparator.new())
+	mission.add_child(_heading("What your support makes possible", 20))
+	for item_text in [
+		"Original question and CCS case development",
+		"Clinical source review and content verification",
+		"Reliable hosting and continued pre-alpha access",
+		"Accessibility, usability, and learning-tool improvements"
+	]:
+		var row := HBoxContainer.new()
+		row.add_theme_constant_override("separation", 12)
+		var marker := Label.new()
+		marker.text = "-"
+		marker.add_theme_font_size_override("font_size", 20)
+		marker.add_theme_color_override("font_color", Brand.TEAL)
+		row.add_child(marker)
+		var item := _body(item_text)
+		item.size_flags_horizontal = Control.SIZE_EXPAND_FILL
+		row.add_child(item)
+		mission.add_child(row)
+
+	contribution_panel = _panel()
+	contribution_panel.size_flags_horizontal = Control.SIZE_EXPAND_FILL
+	content_grid.add_child(contribution_panel)
+	var contribution := VBoxContainer.new()
+	contribution.add_theme_constant_override("separation", 18)
+	contribution_panel.add_child(contribution)
+	contribution.add_child(_heading("Make a one-time contribution", 26))
+	contribution.add_child(_body("Choose an amount. Secure payment and email receipts are handled by Stripe."))
+
+	preset_grid = GridContainer.new()
+	preset_grid.columns = 4
+	preset_grid.add_theme_constant_override("h_separation", 10)
+	preset_grid.add_theme_constant_override("v_separation", 10)
+	contribution.add_child(preset_grid)
+	for amount in [500, 1000, 2500, 5000]:
+		var button := Button.new()
+		button.text = "$%d" % int(amount / 100.0)
+		button.toggle_mode = true
+		button.button_group = amount_group
+		button.custom_minimum_size = Vector2(64, 48)
+		button.size_flags_horizontal = Control.SIZE_EXPAND_FILL
+		button.set_meta("amount_cents", amount)
+		button.pressed.connect(_select_preset.bind(button))
+		preset_grid.add_child(button)
+		amount_buttons.append(button)
+		if amount == DEFAULT_CENTS:
+			button.set_pressed_no_signal(true)
+
+	var custom_label := Label.new()
+	custom_label.text = "Custom amount (USD)"
+	custom_label.add_theme_font_override("font", Brand.font)
+	custom_label.add_theme_font_size_override("font_size", 16)
+	contribution.add_child(custom_label)
+
+	custom_amount = LineEdit.new()
+	custom_amount.placeholder_text = "$5.00 minimum"
+	custom_amount.max_length = 12
+	custom_amount.virtual_keyboard_type = LineEdit.KEYBOARD_TYPE_NUMBER_DECIMAL
+	custom_amount.custom_minimum_size = Vector2(0, 56)
+	custom_amount.text_changed.connect(_on_custom_amount_changed)
+	contribution.add_child(custom_amount)
+
+	donate_button = Button.new()
+	donate_button.text = "Donate $25 securely"
+	donate_button.custom_minimum_size = Vector2(0, 58)
+	donate_button.pressed.connect(_on_donate_pressed)
+	contribution.add_child(donate_button)
+
+	status_label = Label.new()
+	status_label.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
+	status_label.add_theme_font_override("font", Brand.font)
+	status_label.add_theme_font_size_override("font_size", 15)
+	status_label.add_theme_color_override("font_color", Brand.muted_color(UIThemeService.is_dark_mode()))
+	status_label.custom_minimum_size.y = 44
+	contribution.add_child(status_label)
+
+	var disclosure := _body("Contributions are voluntary, one-time, and not tax-deductible. Card details are entered only on Stripe's secure checkout page.")
+	disclosure.add_theme_font_size_override("font_size", 14)
+	contribution.add_child(disclosure)
+
+
+func on_show(_payload: Variant = null) -> void:
+	donate_button.disabled = donation_service.checkout_pending
+	if donation_service.active_donation_id.is_empty():
+		status_label.text = ""
+	else:
+		donation_service.resume_polling()
+
+
+func on_hide() -> void:
+	donation_service.stop_polling()
+
+
+static func parse_amount_cents(value: String) -> int:
+	return DonationAmount.parse_cents(value)
+
+
+func _select_preset(button: Button) -> void:
+	selected_amount_cents = int(button.get_meta("amount_cents", DEFAULT_CENTS))
+	custom_amount.text = ""
+	_set_validation_state("")
+	_update_donate_button()
+	refresh_theme_controls()
+
+
+func _on_custom_amount_changed(value: String) -> void:
+	if value.strip_edges().is_empty():
+		return
+	for button in amount_buttons:
+		button.set_pressed_no_signal(false)
+	selected_amount_cents = parse_amount_cents(value)
+	_set_validation_state("")
+	_update_donate_button()
+	refresh_theme_controls()
+
+
+func _on_donate_pressed() -> void:
+	if selected_amount_cents < MINIMUM_CENTS:
+		_set_validation_state("Enter an amount of at least $5.00.", true)
+		return
+	if selected_amount_cents > MAXIMUM_CENTS:
+		_set_validation_state("The maximum contribution is $10,000.00.", true)
+		return
+	donate_button.disabled = true
+	_set_validation_state("Opening secure checkout...")
+	donation_service.begin_checkout(selected_amount_cents)
+
+
+func _on_checkout_started(_donation_id: String, _checkout_url: String) -> void:
+	donate_button.disabled = false
+	_set_validation_state("Checkout opened in your browser. This page will confirm when Stripe completes the payment.")
+
+
+func _on_donation_status_changed(status: String, _donation: Dictionary) -> void:
+	match status:
+		"paid": _set_validation_state("Thank you for supporting MedMind. Your contribution has been confirmed.", false, Brand.SUCCESS)
+		"failed": _set_validation_state("Stripe could not complete the contribution. No payment was confirmed.", true)
+		"expired": _set_validation_state("The checkout session expired. Start a new checkout when you are ready.", true)
+
+
+func _on_donation_failed(message: String) -> void:
+	donate_button.disabled = false
+	_set_validation_state(message, true)
+
+
+func _update_donate_button() -> void:
+	donate_button.disabled = selected_amount_cents < MINIMUM_CENTS or selected_amount_cents > MAXIMUM_CENTS
+	if selected_amount_cents >= MINIMUM_CENTS and selected_amount_cents <= MAXIMUM_CENTS:
+		donate_button.text = "Donate %s securely" % _format_amount(selected_amount_cents)
+	else:
+		donate_button.text = "Donate securely"
+
+
+func _format_amount(amount_cents: int) -> String:
+	return "$%d.%02d" % [int(amount_cents / 100.0), amount_cents % 100]
+
+
+func _set_validation_state(message: String, is_error: bool = false, color: Color = Color.TRANSPARENT) -> void:
+	status_label.text = message
+	var text_color := color
+	if text_color == Color.TRANSPARENT:
+		text_color = Style.RED if is_error else Brand.muted_color(UIThemeService.is_dark_mode())
+	status_label.add_theme_color_override("font_color", text_color)
+
+
+func _panel() -> PanelContainer:
+	var panel := PanelContainer.new()
+	var box := Brand.content_card_box(UIThemeService.is_dark_mode(), false)
+	box.content_margin_left = 28
+	box.content_margin_right = 28
+	box.content_margin_top = 28
+	box.content_margin_bottom = 28
+	panel.add_theme_stylebox_override("panel", box)
+	return panel
+
+
+func _heading(value: String, font_size: int) -> Label:
+	var label := Label.new()
+	label.text = value
+	label.add_theme_font_override("font", Brand.font)
+	label.add_theme_font_size_override("font_size", font_size)
+	label.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
+	return label
+
+
+func _body(value: String) -> Label:
+	var label := Label.new()
+	label.text = value
+	label.add_theme_font_override("font", Brand.font)
+	label.add_theme_font_size_override("font_size", 17)
+	label.add_theme_color_override("font_color", Brand.muted_color(UIThemeService.is_dark_mode()))
+	label.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
+	return label
+
+
+func _update_layout() -> void:
+	if content_grid != null:
+		content_grid.columns = 1 if size.x < 1050.0 else 2
+	if preset_grid != null:
+		preset_grid.columns = 2 if size.x < 520.0 else 4
+
+
+func refresh_theme_controls() -> void:
+	var dark := UIThemeService.is_dark_mode()
+	for panel in [mission_panel, contribution_panel]:
+		if panel != null:
+			var box := Brand.content_card_box(dark, false)
+			box.content_margin_left = 28
+			box.content_margin_right = 28
+			box.content_margin_top = 28
+			box.content_margin_bottom = 28
+			panel.add_theme_stylebox_override("panel", box)
+	if custom_amount != null:
+		custom_amount.add_theme_stylebox_override("normal", Brand.field_box(dark))
+		custom_amount.add_theme_stylebox_override("focus", Brand.field_box(dark, true))
+		custom_amount.add_theme_color_override("font_color", Brand.text_color(dark))
+		custom_amount.add_theme_color_override("font_placeholder_color", Brand.muted_color(dark))
+	for button in amount_buttons:
+		var selected := button.button_pressed
+		var normal := Brand.secondary_button_box(dark, selected)
+		if selected:
+			normal.bg_color = Color(Brand.ROYAL_BLUE, 0.22 if dark else 0.10)
+			normal.border_color = Brand.ROYAL_BLUE
+		button.add_theme_stylebox_override("normal", normal)
+		button.add_theme_stylebox_override("pressed", normal)
+		button.add_theme_color_override("font_color", Brand.text_color(dark))
+		button.add_theme_color_override("font_pressed_color", Brand.text_color(dark))
+	if donate_button != null:
+		donate_button.add_theme_stylebox_override("normal", Brand.gradient_button_box())
+		donate_button.add_theme_stylebox_override("hover", Brand.gradient_button_box())
+		donate_button.add_theme_color_override("font_color", Color.WHITE)
+		donate_button.add_theme_color_override("font_hover_color", Color.WHITE)
+
+
+func _on_theme_changed(_is_dark_mode: bool) -> void:
+	refresh_theme_controls()
diff --git a/scripts/ui/donation_screen.gd.uid b/scripts/ui/donation_screen.gd.uid
new file mode 100644
index 0000000..38dd1a0
--- /dev/null
+++ b/scripts/ui/donation_screen.gd.uid
@@ -0,0 +1 @@
+uid://i2fix2vkf8au
diff --git a/scripts/ui/main.gd b/scripts/ui/main.gd
index 625c385..2ddff82 100644
--- a/scripts/ui/main.gd
+++ b/scripts/ui/main.gd
@@ -314,6 +314,11 @@ func _build_ui() -> void:
 	bookmarks.main = self
 	screens_container.add_child(bookmarks)
 	screens["bookmarks"] = bookmarks
+	var donations := preload("res://scripts/ui/donation_screen.gd").new()
+	donations.name = "DonationScreen"
+	donations.main = self
+	screens_container.add_child(donations)
+	screens["donations"] = donations
 
 	feedback_dialog = preload("res://scripts/ui/app_feedback_dialog.gd").new()
 	feedback_dialog.name = "AppFeedbackDialog"
@@ -386,6 +391,7 @@ func _populate_navigation(container: VBoxContainer, include_brand: bool) -> void
 	spacer.size_flags_vertical = Control.SIZE_EXPAND_FILL
 	container.add_child(spacer)
 	container.add_child(HSeparator.new())
+	_add_nav_button(container, "donations", "Support MedMind", "heart-pulse", true)
 	_add_nav_button(container, "performance", "Profile", "user-round", true)
 	_add_nav_button(container, "settings", "Settings", "settings", true)
 	_add_nav_button(container, "logout", "Log out", "log-out", true)
@@ -426,6 +432,7 @@ func _on_navigation_pressed(key: String) -> void:
 		"settings": show_screen("settings")
 		"notes": show_screen("notes")
 		"bookmarks": show_screen("bookmarks")
+		"donations": show_screen("donations")
 		"logout": _logout()
 
 
@@ -440,7 +447,8 @@ func _update_header_title(screen_name: String) -> void:
 		"profile": "Profile",
 		"settings": "Settings",
 		"notes": "Notes",
-		"bookmarks": "Bookmarks"
+		"bookmarks": "Bookmarks",
+		"donations": "Support MedMind"
 	}
 	header_title.text = str(titles.get(screen_name, ""))
 
@@ -735,6 +743,9 @@ func _on_theme_changed(is_dark_mode: bool) -> void:
 	var selector = screens.get("selection")
 	if selector != null and selector.has_method("refresh_theme_controls"):
 		selector.refresh_theme_controls()
+	var donations = screens.get("donations")
+	if donations != null and donations.has_method("refresh_theme_controls"):
+		donations.refresh_theme_controls()
 	var player = screens.get("player")
 	if player != null and player.has_method("refresh_theme_controls"):
 		player.refresh_theme_controls()
diff --git a/scripts/ui/navigation_routes.gd b/scripts/ui/navigation_routes.gd
index 262fc0b..0c53738 100644
--- a/scripts/ui/navigation_routes.gd
+++ b/scripts/ui/navigation_routes.gd
@@ -23,4 +23,6 @@ static func key_for_screen(screen_name: String, payload: Variant = null) -> Stri
 		key = "notes"
 	elif screen_name == "bookmarks":
 		key = "bookmarks"
+	elif screen_name == "donations":
+		key = "donations"
 	return key
diff --git a/tests/donation_screen_test.gd b/tests/donation_screen_test.gd
new file mode 100644
index 0000000..fa9bb7c
--- /dev/null
+++ b/tests/donation_screen_test.gd
@@ -0,0 +1,21 @@
+extends SceneTree
+
+const DonationAmount := preload("res://scripts/ui/donation_amount.gd")
+
+var failures := 0
+
+
+func _initialize() -> void:
+	_assert(DonationAmount.parse_cents("5") == 500, "whole dollars should parse")
+	_assert(DonationAmount.parse_cents("$25.50") == 2550, "dollars and cents should parse")
+	_assert(DonationAmount.parse_cents("4.999") == -1, "more than two decimal places should fail")
+	_assert(DonationAmount.parse_cents("10000.01") == -1, "amounts above the cap should fail")
+	_assert(DonationAmount.parse_cents("abc") == -1, "non-numeric values should fail")
+	quit(1 if failures > 0 else 0)
+
+
+func _assert(condition: bool, message: String) -> void:
+	if condition:
+		return
+	failures += 1
+	push_error(message)
diff --git a/tests/donation_screen_test.gd.uid b/tests/donation_screen_test.gd.uid
new file mode 100644
index 0000000..59c6445
--- /dev/null
+++ b/tests/donation_screen_test.gd.uid
@@ -0,0 +1 @@
+uid://d0ik8fhaa2u8w
diff --git a/tests/donation_ui_test.gd b/tests/donation_ui_test.gd
new file mode 100644
index 0000000..5db77fa
--- /dev/null
+++ b/tests/donation_ui_test.gd
@@ -0,0 +1,47 @@
+extends SceneTree
+
+var failures := 0
+
+
+func _initialize() -> void:
+	call_deferred("_run")
+
+
+func _run() -> void:
+	var theme_service = root.get_node("UIThemeService")
+	var prior_dark_mode: bool = theme_service.is_dark_mode()
+	var host := Control.new()
+	host.size = Vector2(1280, 800)
+	root.add_child(host)
+	var screen = load("res://scripts/ui/donation_screen.gd").new()
+	screen.size = host.size
+	host.add_child(screen)
+	await process_frame
+	_assert(screen.content_grid.columns == 2, "wide donation layouts should use two columns")
+	_assert(screen.selected_amount_cents == 2500, "the default preset should be $25")
+	_assert(screen.donate_button.text.contains("$25.00"), "the donation action should state the selected amount")
+	screen.size = Vector2(760, 800)
+	screen._update_layout()
+	_assert(screen.content_grid.columns == 1, "narrow donation layouts should stack")
+	screen.size = Vector2(360, 800)
+	screen._update_layout()
+	_assert(screen.preset_grid.columns == 2, "phone donation layouts should use a two-column amount grid")
+	screen.custom_amount.text = "4"
+	screen._on_custom_amount_changed("4")
+	await process_frame
+	_assert(screen.donate_button.disabled, "amounts below $5 should disable checkout")
+	theme_service.set_dark_mode(false)
+	await process_frame
+	var light_box := screen.mission_panel.get_theme_stylebox("panel") as StyleBoxFlat
+	_assert(light_box.bg_color.is_equal_approx(Color.WHITE), "donation cards should use light surfaces in light mode")
+	host.queue_free()
+	await process_frame
+	theme_service.set_dark_mode(prior_dark_mode)
+	quit(1 if failures > 0 else 0)
+
+
+func _assert(condition: bool, message: String) -> void:
+	if condition:
+		return
+	failures += 1
+	push_error(message)
diff --git a/tests/donation_ui_test.gd.uid b/tests/donation_ui_test.gd.uid
new file mode 100644
index 0000000..0f3fe43
--- /dev/null
+++ b/tests/donation_ui_test.gd.uid
@@ -0,0 +1 @@
+uid://cfg0oxxrtumdj
diff --git a/tests/shell_navigation_test.gd b/tests/shell_navigation_test.gd
index ad9a4d2..8ca8a57 100644
--- a/tests/shell_navigation_test.gd
+++ b/tests/shell_navigation_test.gd
@@ -19,6 +19,7 @@ func _initialize() -> void:
 	_assert(NavigationRoutes.key_for_screen("settings") == "settings", "settings should activate Settings")
 	_assert(NavigationRoutes.key_for_screen("notes") == "notes", "notes should activate Notes")
 	_assert(NavigationRoutes.key_for_screen("bookmarks") == "bookmarks", "bookmarks should activate Bookmarks")
+	_assert(NavigationRoutes.key_for_screen("donations") == "donations", "donations should activate Support MedMind")
 	quit(1 if failures > 0 else 0)
 
 
diff --git a/tests/web_responsive_test.gd b/tests/web_responsive_test.gd
index 40623e2..e091b46 100644
--- a/tests/web_responsive_test.gd
+++ b/tests/web_responsive_test.gd
@@ -74,6 +74,8 @@ func _run() -> void:
 	_assert(main_screen.sidebar.find_child("NavPractice", true, false) == null, "the sidebar should not retain a Practice navigation item")
 	var profile_nav := main_screen.sidebar.find_child("NavPerformance", true, false) as Button
 	var settings_nav := main_screen.sidebar.find_child("NavSettings", true, false) as Button
+	var donation_nav := main_screen.sidebar.find_child("NavDonations", true, false) as Button
+	_assert(donation_nav != null and donation_nav.text == "Support MedMind", "the shell should expose donation navigation")
 	_assert(profile_nav != null and settings_nav != null and profile_nav.get_index() + 1 == settings_nav.get_index(), "Profile should sit directly above Settings in the lower navigation group")
 	var theme_service = root.get_node("UIThemeService")
 	var prior_dark_mode: bool = theme_service.is_dark_mode()
diff --git a/web/Dockerfile b/web/Dockerfile
index 8ea3e0b..ff9e6c3 100644
--- a/web/Dockerfile
+++ b/web/Dockerfile
@@ -35,9 +35,13 @@ RUN mkdir -p /build \
     && godot --verbose --headless --path /src --export-release Web /build/index.html \
     && cp /src/assets/branding/medmind-loader-mark.png /build/medmind-loader-icon.png \
     && cp /src/assets/fonts/Inter-Variable.ttf /build/medmind-inter.ttf \
+    && cp /src/web/donation-complete.html /build/donation-complete.html \
+    && cp /src/web/donation-canceled.html /build/donation-canceled.html \
     && test -s /build/index.html \
     && test -s /build/medmind-loader-icon.png \
     && test -s /build/medmind-inter.ttf \
+    && test -s /build/donation-complete.html \
+    && test -s /build/donation-canceled.html \
     && test -s /build/index.wasm \
     && test -s /build/index.pck
 
diff --git a/web/donation-canceled.html b/web/donation-canceled.html
new file mode 100644
index 0000000..7a75d7e
--- /dev/null
+++ b/web/donation-canceled.html
@@ -0,0 +1,19 @@
+<!doctype html>
+<html lang="en">
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width,initial-scale=1">
+  <title>Checkout canceled | MedMind</title>
+  <style>
+    @font-face{font-family:Inter;src:url('/medmind-inter.ttf') format('truetype');font-display:swap}
+    :root{color-scheme:dark light;--bg:#071224;--surface:#0b1427;--border:#33415d;--text:#f8fafc;--muted:#a9b5ca;--accent:#38bdf8}
+    @media(prefers-color-scheme:light){:root{--bg:#f1f5f9;--surface:#fff;--border:#dbe3ef;--text:#0f172a;--muted:#64748b}}
+    :root[data-theme=light]{--bg:#f1f5f9;--surface:#fff;--border:#dbe3ef;--text:#0f172a;--muted:#64748b}
+    *{box-sizing:border-box}body{margin:0;min-height:100vh;display:grid;place-items:center;padding:24px;background:var(--bg);color:var(--text);font-family:Inter,system-ui,sans-serif}
+    main{width:min(560px,100%);padding:40px;border:1px solid var(--border);border-radius:12px;background:var(--surface);text-align:center}
+    img{width:84px;height:84px;object-fit:contain}h1{margin:22px 0 12px;font-size:30px}p{margin:0;color:var(--muted);font-size:17px;line-height:1.6}
+  </style>
+</head>
+<script>try{document.documentElement.dataset.theme=localStorage.getItem('medmind-color-scheme')||''}catch(e){}</script>
+<body><main><img src="/medmind-loader-icon.png" alt="MedMind"><h1>Checkout canceled</h1><p>No contribution was completed. You can close this tab and return to MedMind.</p></main></body>
+</html>
diff --git a/web/donation-complete.html b/web/donation-complete.html
new file mode 100644
index 0000000..93bcf6e
--- /dev/null
+++ b/web/donation-complete.html
@@ -0,0 +1,19 @@
+<!doctype html>
+<html lang="en">
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width,initial-scale=1">
+  <title>Contribution received | MedMind</title>
+  <style>
+    @font-face{font-family:Inter;src:url('/medmind-inter.ttf') format('truetype');font-display:swap}
+    :root{color-scheme:dark light;--bg:#071224;--surface:#0b1427;--border:#33415d;--text:#f8fafc;--muted:#a9b5ca;--accent:#38bdf8;--success:#22c55e}
+    @media(prefers-color-scheme:light){:root{--bg:#f1f5f9;--surface:#fff;--border:#dbe3ef;--text:#0f172a;--muted:#64748b}}
+    :root[data-theme=light]{--bg:#f1f5f9;--surface:#fff;--border:#dbe3ef;--text:#0f172a;--muted:#64748b}
+    *{box-sizing:border-box}body{margin:0;min-height:100vh;display:grid;place-items:center;padding:24px;background:var(--bg);color:var(--text);font-family:Inter,system-ui,sans-serif}
+    main{width:min(560px,100%);padding:40px;border:1px solid var(--border);border-radius:12px;background:var(--surface);text-align:center}
+    img{width:84px;height:84px;object-fit:contain}h1{margin:22px 0 12px;font-size:30px}p{margin:0;color:var(--muted);font-size:17px;line-height:1.6}.status{color:var(--success);font-weight:700}
+  </style>
+</head>
+<script>try{document.documentElement.dataset.theme=localStorage.getItem('medmind-color-scheme')||''}catch(e){}</script>
+<body><main><img src="/medmind-loader-icon.png" alt="MedMind"><h1>Thank you for supporting MedMind</h1><p class="status">Your checkout is complete.</p><p>You can close this tab and return to MedMind. Stripe will send your receipt by email.</p></main></body>
+</html>