diff --git a/modules/auth/controllers/auth.controller.js b/modules/auth/controllers/auth.controller.js
index 81154a715..04d0d1d4e 100644
--- a/modules/auth/controllers/auth.controller.js
+++ b/modules/auth/controllers/auth.controller.js
@@ -7,6 +7,7 @@ import jwt from 'jsonwebtoken';
 
 import UserService from '../../users/services/users.service.js';
 import InvitationService from '../services/auth.invitation.service.js';
+import { computeSignupCapacity } from '../services/auth.signupCapacity.js';
 import config from '../../../config/index.js';
 import model from '../../../lib/middlewares/model.js';
 import mails from '../../../lib/helpers/mailer/index.js';
@@ -601,43 +602,50 @@ const signout = (req, res) => {
  * @desc Endpoint to expose public auth configuration (sign flags and organizations settings)
  * @param {Object} req - Express request object
  * @param {Object} res - Express response object
- * @returns {void} Sends the public auth configuration in the HTTP response
+ * @returns {Promise<void>} Sends the public auth configuration in the HTTP response
  */
-const getConfig = (req, res) => {
-  const data = {
-    sign: {
-      in: !!config.sign.in,
-      up: !!config.sign.up,
-    },
-    oAuth: {
-      google: !!config.oAuth?.google?.clientID,
-      apple: !!config.oAuth?.apple?.clientID,
-    },
-    organizations: {
-      enabled: !!config.organizations?.enabled,
-      domainMatching: !!config.organizations?.domainMatching,
-      autoCreate: !!config.organizations?.autoCreate,
-    },
-    mail: {
-      configured: isMailerConfigured(),
-    },
-  };
-
-  // Authenticated users get extended org config and billing config
-  if (req.user) {
-    data.organizations = {
-      ...data.organizations,
-      roles: config.organizations?.roles || [],
-      roleDescriptions: config.organizations?.roleDescriptions || {},
-    };
-    data.billing = {
-      enabled: !!config.billing?.enabled,
-      meterMode: !!config.billing?.meterMode,
-      equivalences: config.billing?.equivalences ?? null,
+const getConfig = async (req, res) => {
+  try {
+    const { cap, remaining } = await computeSignupCapacity(config.sign?.cap, UserService.count);
+    const data = {
+      sign: {
+        in: !!config.sign.in,
+        up: !!config.sign.up,
+        cap, // null = uncapped; numeric = hard ceiling on total accounts (invited included)
+        remaining, // null = uncapped; else max(0, cap - totalAccounts)
+      },
+      oAuth: {
+        google: !!config.oAuth?.google?.clientID,
+        apple: !!config.oAuth?.apple?.clientID,
+      },
+      organizations: {
+        enabled: !!config.organizations?.enabled,
+        domainMatching: !!config.organizations?.domainMatching,
+        autoCreate: !!config.organizations?.autoCreate,
+      },
+      mail: {
+        configured: isMailerConfigured(),
+      },
     };
-  }
 
-  responses.success(res, 'Auth config')(data);
+    // Authenticated users get extended org config and billing config
+    if (req.user) {
+      data.organizations = {
+        ...data.organizations,
+        roles: config.organizations?.roles || [],
+        roleDescriptions: config.organizations?.roleDescriptions || {},
+      };
+      data.billing = {
+        enabled: !!config.billing?.enabled,
+        meterMode: !!config.billing?.meterMode,
+        equivalences: config.billing?.equivalences ?? null,
+      };
+    }
+
+    responses.success(res, 'Auth config')(data);
+  } catch (err) {
+    responses.error(res, 422, 'Unprocessable Entity', errors.getMessage(err))(err);
+  }
 };
 
 /**
diff --git a/modules/auth/services/auth.signupCapacity.js b/modules/auth/services/auth.signupCapacity.js
new file mode 100644
index 000000000..ea354e952
--- /dev/null
+++ b/modules/auth/services/auth.signupCapacity.js
@@ -0,0 +1,15 @@
+/**
+ * @desc Compute the public beta-capacity view for the auth config endpoint:
+ * the configured cap and how many seats remain. Skips the (collection-wide)
+ * count entirely when uncapped or when cap ≤ 0 (remaining is deterministically 0).
+ * @param {number|string|null|undefined} rawCap - config.sign.cap (null/undefined/non-numeric/blank = uncapped; 0 = fully closed, 0 seats)
+ * @param {() => Promise<number>} countFn - async total-account counter (UserService.count)
+ * @returns {Promise<{cap: number|null, remaining: number|null}>}
+ */
+export const computeSignupCapacity = async (rawCap, countFn) => {
+  const cap = rawCap != null && String(rawCap).trim() !== '' ? Number(rawCap) : null;
+  if (cap == null || !Number.isFinite(cap)) return { cap: null, remaining: null };
+  if (cap <= 0) return { cap, remaining: 0 };
+  const remaining = Math.max(0, cap - (await countFn()));
+  return { cap, remaining };
+};
diff --git a/modules/auth/tests/auth.config.controller.unit.tests.js b/modules/auth/tests/auth.config.controller.unit.tests.js
index 71016936a..8c73f9b4d 100644
--- a/modules/auth/tests/auth.config.controller.unit.tests.js
+++ b/modules/auth/tests/auth.config.controller.unit.tests.js
@@ -106,11 +106,14 @@ describe('auth.controller getConfig:', () => {
     const req = {}; // no req.user
     const res = {};
 
-    AuthController.getConfig(req, res);
+    await AuthController.getConfig(req, res);
 
     expect(responses.success).toHaveBeenCalledWith(res, 'Auth config');
     const [data] = mockResponses.successCb.mock.calls[0];
     expect(data.billing).toBeUndefined();
+    // sign.cap / sign.remaining must be null when config.sign has no cap (uncapped path)
+    expect(data.sign.cap).toBeNull();
+    expect(data.sign.remaining).toBeNull();
   });
 
   test('data.billing defaults to false/false/null when config.billing is undefined (authenticated)', async () => {
@@ -120,7 +123,7 @@ describe('auth.controller getConfig:', () => {
     const req = { user: { id: '1' } };
     const res = {};
 
-    AuthController.getConfig(req, res);
+    await AuthController.getConfig(req, res);
 
     const [data] = mockResponses.successCb.mock.calls[0];
     expect(data.billing).toBeDefined();
@@ -137,7 +140,7 @@ describe('auth.controller getConfig:', () => {
     const req = { user: { id: '1' } };
     const res = {};
 
-    AuthController.getConfig(req, res);
+    await AuthController.getConfig(req, res);
 
     const [data] = mockResponses.successCb.mock.calls[0];
     expect(data.billing).toBeDefined();
@@ -160,7 +163,7 @@ describe('auth.controller getConfig:', () => {
     const req = { user: { id: '1' } };
     const res = {};
 
-    AuthController.getConfig(req, res);
+    await AuthController.getConfig(req, res);
 
     const [data] = mockResponses.successCb.mock.calls[0];
     expect(data.billing.equivalences).toEqual(equivalences);
diff --git a/modules/auth/tests/auth.signupCapacity.unit.tests.js b/modules/auth/tests/auth.signupCapacity.unit.tests.js
new file mode 100644
index 000000000..7bd6a3cba
--- /dev/null
+++ b/modules/auth/tests/auth.signupCapacity.unit.tests.js
@@ -0,0 +1,55 @@
+import { jest } from '@jest/globals';
+import { computeSignupCapacity } from '../services/auth.signupCapacity.js';
+
+describe('computeSignupCapacity', () => {
+  test('uncapped (null) → {cap:null, remaining:null} and count() not called', async () => {
+    const countFn = jest.fn();
+    await expect(computeSignupCapacity(null, countFn)).resolves.toEqual({ cap: null, remaining: null });
+    expect(countFn).not.toHaveBeenCalled();
+  });
+
+  test('uncapped (undefined) → {cap:null, remaining:null}', async () => {
+    const countFn = jest.fn();
+    await expect(computeSignupCapacity(undefined, countFn)).resolves.toEqual({ cap: null, remaining: null });
+    expect(countFn).not.toHaveBeenCalled();
+  });
+
+  test('capped → remaining = cap - count', async () => {
+    const countFn = jest.fn().mockResolvedValue(10);
+    await expect(computeSignupCapacity(50, countFn)).resolves.toEqual({ cap: 50, remaining: 40 });
+  });
+
+  test('at/over cap → remaining floored at 0', async () => {
+    const countFn = jest.fn().mockResolvedValue(60);
+    await expect(computeSignupCapacity(50, countFn)).resolves.toEqual({ cap: 50, remaining: 0 });
+  });
+
+  test('non-numeric cap → treated as uncapped', async () => {
+    const countFn = jest.fn();
+    await expect(computeSignupCapacity('abc', countFn)).resolves.toEqual({ cap: null, remaining: null });
+    expect(countFn).not.toHaveBeenCalled();
+  });
+
+  test('empty string cap → treated as uncapped (not coerced to 0)', async () => {
+    const countFn = jest.fn();
+    await expect(computeSignupCapacity('', countFn)).resolves.toEqual({ cap: null, remaining: null });
+    expect(countFn).not.toHaveBeenCalled();
+  });
+
+  test('whitespace-only cap → treated as uncapped (not coerced to 0)', async () => {
+    const countFn = jest.fn();
+    await expect(computeSignupCapacity('   ', countFn)).resolves.toEqual({ cap: null, remaining: null });
+    expect(countFn).not.toHaveBeenCalled();
+  });
+
+  test('cap = 0 → fully closed: {cap:0, remaining:0} and count is NOT called (short-circuit)', async () => {
+    const countFn = jest.fn();
+    await expect(computeSignupCapacity(0, countFn)).resolves.toEqual({ cap: 0, remaining: 0 });
+    expect(countFn).not.toHaveBeenCalled();
+  });
+
+  test('numeric string cap ("42") → coerced: {cap:42, remaining:40}', async () => {
+    const countFn = jest.fn().mockResolvedValue(2);
+    await expect(computeSignupCapacity('42', countFn)).resolves.toEqual({ cap: 42, remaining: 40 });
+  });
+});