diff --git a/stellar-payment-platform/server.js b/stellar-payment-platform/server.js
index c55c098e..d1565f29 100644
--- a/stellar-payment-platform/server.js
+++ b/stellar-payment-platform/server.js
@@ -32,6 +32,7 @@ const { validateSchema } = require('./src/middleware/validateSchema');
 const { buildErrorHandler, notFoundHandler } = require('./src/middleware/errorHandler');
 const { ApiError, errorBody } = require('./src/errors');
 const { requireJson } = require('./src/middleware/requireJson');
+const { bodySizeLimit } = require('./src/middleware/bodyLimit');
 const { apiVersion } = require('./src/middleware/apiVersion');
 const {
   registerBodySchema,
@@ -203,10 +204,13 @@ const limiter = rateLimit({
 });
 
 app.use(cors(corsOptions));
-app.use(express.json());
+
+// #588 — Per-route request body size limits. A single JSON parser enforces a
+// cap that depends on the endpoint type (auth 1kb / standard 10kb / bulk 100kb)
+// instead of the previous uniform 10kb, and answers oversized payloads with 413.
+app.use(bodySizeLimit);
 
 app.use(limiter);
-app.use(express.json({ limit: '10kb' }));
 const isPrimitive = (v) => v === null || v === undefined || typeof v !== 'object';
 
 const rejectNestedObjects = (req, res, next) => {
diff --git a/stellar-payment-platform/src/middleware/bodyLimit.js b/stellar-payment-platform/src/middleware/bodyLimit.js
new file mode 100644
index 00000000..2d2738be
--- /dev/null
+++ b/stellar-payment-platform/src/middleware/bodyLimit.js
@@ -0,0 +1,91 @@
+'use strict';
+
+const express = require('express');
+
+/**
+ * #588 — Per-route request body size limits.
+ *
+ * A single global JSON parser enforces a cap that depends on the endpoint
+ * type, so the cap travels with the request regardless of mount point:
+ *
+ *   - Auth / register endpoints: 1kb  (tighter, to blunt abuse)
+ *   - Bulk endpoints (/payments, /webhooks): 100kb (legitimate large payloads)
+ *   - Everything else: 10kb (standard)
+ *
+ * body-parser already answers an oversized payload with a 413
+ * (`entity.too.large`), which the error handler turns into the standard
+ * envelope. The resolved byte limit is stashed on `req.bodySizeLimit` so the
+ * 413 message can name the exact cap that was exceeded.
+ *
+ * NOTE: the installed raw-body only honours numeric / string `limit` values
+ * (not a per-request function), so we dispatch to one of three pre-built
+ * parsers based on the request path instead of using limit-as-a-function.
+ */
+
+const KB = 1024;
+
+const AUTH_LIMIT = 1 * KB;
+const STANDARD_LIMIT = 10 * KB;
+const BULK_LIMIT = 100 * KB;
+
+// Per-route tiers are intentionally explicit so the mapping is easy to audit
+// and extend. Matched against the path portion of the request URL (no query).
+const AUTH_PATTERNS = [
+  /^\/register(\/|$)/i,
+  /^\/auth(\/|$)/i,
+];
+
+const BULK_PATTERNS = [
+  /\/payments(\/|$)/i,
+  /\/webhooks(\/|$)/i,
+];
+
+/**
+ * Resolve the byte limit for a request based on its path.
+ *
+ * @param {string} url full request URL (req.originalUrl)
+ * @returns {number} maximum body size in bytes
+ */
+const limitForPath = (url) => {
+  const path = (url || '').split('?')[0];
+
+  if (AUTH_PATTERNS.some((re) => re.test(path))) {
+    return AUTH_LIMIT;
+  }
+  if (BULK_PATTERNS.some((re) => re.test(path))) {
+    return BULK_LIMIT;
+  }
+  return STANDARD_LIMIT;
+};
+
+// Pre-built parsers — each carries an explicit numeric limit that raw-body can
+// enforce. The dispatcher below picks the right one per request.
+const authParser = express.json({ limit: AUTH_LIMIT });
+const standardParser = express.json({ limit: STANDARD_LIMIT });
+const bulkParser = express.json({ limit: BULK_LIMIT });
+
+/**
+ * Express middleware that applies the per-route body size limit. It forwards to
+ * the appropriate pre-built JSON parser for the request path, recording the
+ * resolved cap on `req.bodySizeLimit` for downstream error reporting.
+ */
+const bodySizeLimit = (req, res, next) => {
+  const bytes = limitForPath(req.originalUrl);
+  req.bodySizeLimit = bytes;
+
+  const parser =
+    bytes === AUTH_LIMIT ? authParser
+      : bytes === BULK_LIMIT ? bulkParser
+        : standardParser;
+
+  return parser(req, res, next);
+};
+
+module.exports = {
+  KB,
+  AUTH_LIMIT,
+  STANDARD_LIMIT,
+  BULK_LIMIT,
+  limitForPath,
+  bodySizeLimit,
+};
diff --git a/stellar-payment-platform/src/middleware/errorHandler.js b/stellar-payment-platform/src/middleware/errorHandler.js
index 500b5fe4..cd6cd8f6 100644
--- a/stellar-payment-platform/src/middleware/errorHandler.js
+++ b/stellar-payment-platform/src/middleware/errorHandler.js
@@ -8,7 +8,7 @@ const { ApiError, codeForStatus, errorBody, DEFAULT_MESSAGES } = require('../err
  * Maps errors thrown by libraries, which carry their own conventions rather
  * than a code, onto the platform's codes.
  */
-const classify = (err, isPrismaConnectionError) => {
+const classify = (err, req, isPrismaConnectionError) => {
   if (err instanceof ApiError) {
     return {
       code: err.code,
@@ -30,10 +30,12 @@ const classify = (err, isPrismaConnectionError) => {
 
   // body-parser rejects oversized payloads with its own type tag.
   if (err.type === 'entity.too.large') {
+    const bytes = req && req.bodySizeLimit;
+    const maxKb = bytes ? Math.round(bytes / 1024) : 10;
     return {
       code: 'PAYLOAD_TOO_LARGE',
       statusCode: 413,
-      message: 'Payload too large. Maximum allowed size is 10kb.',
+      message: `Payload too large. Maximum allowed size for this endpoint is ${maxKb}kb.`,
     };
   }
 
@@ -67,7 +69,7 @@ const classify = (err, isPrismaConnectionError) => {
 const buildErrorHandler = (isPrismaConnectionError) =>
   // eslint-disable-next-line no-unused-vars
   (err, req, res, _next) => {
-    const { code, statusCode, message, details, expected } = classify(err, isPrismaConnectionError);
+    const { code, statusCode, message, details, expected } = classify(err, req, isPrismaConnectionError);
 
     if (res.headersSent) {
       return;
diff --git a/stellar-payment-platform/tests/middleware/bodyLimit.test.js b/stellar-payment-platform/tests/middleware/bodyLimit.test.js
new file mode 100644
index 00000000..9126d6e4
--- /dev/null
+++ b/stellar-payment-platform/tests/middleware/bodyLimit.test.js
@@ -0,0 +1,105 @@
+'use strict';
+
+const express = require('express');
+const request = require('supertest');
+
+const mockLogger = { error: jest.fn(), warn: jest.fn(), info: jest.fn(), debug: jest.fn() };
+jest.mock('../../src/logger', () => ({ logger: mockLogger }));
+
+const { bodySizeLimit } = require('../../src/middleware/bodyLimit');
+const { buildErrorHandler } = require('../../src/middleware/errorHandler');
+
+const buildApp = (path, handler) => {
+  const app = express();
+  app.use((req, res, next) => {
+    req.correlationId = 'test-correlation-id';
+    next();
+  });
+  // #588 — same wiring server.js uses: per-route limit, then the terminal 413
+  // handler that turns body-parser's entity.too.large into the envelope.
+  app.use(bodySizeLimit);
+  app.post(path, handler || ((req, res) => res.json({ ok: true, bytes: JSON.stringify(req.body).length })));
+  app.use(buildErrorHandler(() => false));
+  return app;
+};
+
+// A payload just over a given kb ceiling.
+const over = (kb) => 'x'.repeat(kb * 1024 + 1);
+const under = (kb) => 'x'.repeat(kb * 1024);
+
+describe('body size limits (#588)', () => {
+  test('auth endpoint rejects payloads over 1kb with 413', async () => {
+    const res = await request(buildApp('/register'))
+      .post('/register')
+      .set('Content-Type', 'application/json')
+      .send(over(1));
+    expect(res.status).toBe(413);
+    expect(res.body.error.code).toBe('PAYLOAD_TOO_LARGE');
+    expect(res.body.error.message).toMatch(/1kb/);
+  });
+
+  test('auth endpoint accepts payloads within 1kb', async () => {
+    const res = await request(buildApp('/register'))
+      .post('/register')
+      .set('Content-Type', 'application/json')
+      .send({ username: 'alice', address: 'GABCDEFGHIJKLMNOP' });
+    expect(res.status).toBeLessThan(400);
+  });
+
+  test('bulk /payments endpoint accepts payloads up to 100kb', async () => {
+    const res = await request(buildApp('/api/v1/payments/bulk'))
+      .post('/api/v1/payments/bulk')
+      .set('Content-Type', 'application/json')
+      .send({ intents: under(50) });
+    expect(res.status).toBeLessThan(400);
+  });
+
+  test('bulk /payments endpoint rejects payloads over 100kb', async () => {
+    const res = await request(buildApp('/api/v1/payments/bulk'))
+      .post('/api/v1/payments/bulk')
+      .set('Content-Type', 'application/json')
+      .send({ intents: over(100) });
+    expect(res.status).toBe(413);
+    expect(res.body.error.message).toMatch(/100kb/);
+  });
+
+  test('bulk /webhooks endpoint accepts up to 100kb and rejects over', async () => {
+    const ok = await request(buildApp('/api/v1/webhooks'))
+      .post('/api/v1/webhooks')
+      .set('Content-Type', 'application/json')
+      .send({ url: 'https://example.com', username: under(50) });
+    expect(ok.status).toBeLessThan(400);
+
+    const res = await request(buildApp('/api/v1/webhooks'))
+      .post('/api/v1/webhooks')
+      .set('Content-Type', 'application/json')
+      .send({ url: 'https://example.com', username: over(100) });
+    expect(res.status).toBe(413);
+    expect(res.body.error.message).toMatch(/100kb/);
+  });
+
+  test('standard endpoints reject payloads over 10kb', async () => {
+    const res = await request(buildApp('/api/v1/users'))
+      .post('/api/v1/users')
+      .set('Content-Type', 'application/json')
+      .send({ data: over(10) });
+    expect(res.status).toBe(413);
+    expect(res.body.error.message).toMatch(/10kb/);
+  });
+
+  test('standard endpoints accept payloads within 10kb', async () => {
+    const res = await request(buildApp('/api/v1/users'))
+      .post('/api/v1/users')
+      .set('Content-Type', 'application/json')
+      .send({ data: under(5) });
+    expect(res.status).toBeLessThan(400);
+  });
+
+  test('non-JSON bodies are not parsed or limited', async () => {
+    const res = await request(buildApp('/api/v1/users'))
+      .post('/api/v1/users')
+      .set('Content-Type', 'text/plain')
+      .send(over(1000));
+    expect(res.status).not.toBe(413);
+  });
+});