diff --git a/packages/core/src/__mocks__/index.ts b/packages/core/src/__mocks__/index.ts
index 47eb23adf..9c3c5ff6f 100644
--- a/packages/core/src/__mocks__/index.ts
+++ b/packages/core/src/__mocks__/index.ts
@@ -14,6 +14,7 @@ export * from './user';
 
 export const mockApplication: Application = {
   id: 'foo',
+  secret: 'randomId',
   name: 'foo',
   type: ApplicationType.SPA,
   description: null,
diff --git a/packages/core/src/database/seed.ts b/packages/core/src/database/seed.ts
index c0bc3ab05..1ab9bca58 100644
--- a/packages/core/src/database/seed.ts
+++ b/packages/core/src/database/seed.ts
@@ -8,6 +8,8 @@ import { createPool, parseDsn, sql, stringifyDsn } from 'slonik';
 import { createInterceptors } from 'slonik-interceptor-preset';
 import { raw } from 'slonik-sql-tag-raw';
 
+import { buildApplicationSecret } from '@/utils/id';
+
 import { convertToPrimitiveOrSql } from './utils';
 
 const {
@@ -84,7 +86,7 @@ export const createDatabaseCli = (dsn: string) => {
       pool.query(insertInto(managementResource, 'resources')),
       pool.query(insertInto(createDefaultSetting(), 'settings')),
       pool.query(insertInto(defaultSignInExperience, 'sign_in_experiences')),
-      pool.query(insertInto(createDemoAppApplication(), 'applications')),
+      pool.query(insertInto(createDemoAppApplication(buildApplicationSecret()), 'applications')),
       pool.query(insertInto(defaultRole, 'roles')),
     ]);
     console.log(`${chalk.blue('[seed-tables]')} Seed tables succeeded.`);
diff --git a/packages/core/src/oidc/adapter.test.ts b/packages/core/src/oidc/adapter.test.ts
index 46cd4d905..36dc24130 100644
--- a/packages/core/src/oidc/adapter.test.ts
+++ b/packages/core/src/oidc/adapter.test.ts
@@ -27,6 +27,11 @@ jest.mock('@/queries/oidc-model-instance', () => ({
   revokeInstanceByGrantId: jest.fn(),
 }));
 
+jest.mock('@/utils/id', () => ({
+  // eslint-disable-next-line unicorn/consistent-function-scoping
+  buildIdGenerator: jest.fn(() => () => 'randomId'),
+}));
+
 const now = Date.now();
 
 jest.mock(
@@ -54,6 +59,7 @@ describe('postgres Adapter', () => {
     const {
       id: client_id,
       name: client_name,
+      secret: client_secret,
       type,
       oidcClientMetadata,
       customClientMetadata,
@@ -62,6 +68,7 @@ describe('postgres Adapter', () => {
     expect(application).toEqual({
       client_id,
       client_name,
+      client_secret,
       application_type: getApplicationTypeString(type),
       grant_types: ['authorization_code', 'refresh_token'],
       token_endpoint_auth_method: 'none',
diff --git a/packages/core/src/oidc/adapter.ts b/packages/core/src/oidc/adapter.ts
index 3a2de6dc9..c65124665 100644
--- a/packages/core/src/oidc/adapter.ts
+++ b/packages/core/src/oidc/adapter.ts
@@ -57,16 +57,19 @@ export default function postgresAdapter(modelName: string): ReturnType<AdapterFa
     const reject = async () => Promise.reject(new Error('Not implemented'));
     const transpileClient = ({
       id: client_id,
+      secret: client_secret,
       name: client_name,
       type,
       oidcClientMetadata,
       customClientMetadata,
     }: CreateApplication): AllClientMetadata => ({
       client_id,
+      client_secret,
       client_name,
       application_type: getApplicationTypeString(type),
       grant_types: Object.values(GrantType),
-      token_endpoint_auth_method: 'none',
+      token_endpoint_auth_method:
+        type === ApplicationType.Traditional ? 'client_secret_basic' : 'none',
       ...snakecaseKeys(oidcClientMetadata),
       ...(client_id === demoAppApplicationId &&
         snakecaseKeys(buildDemoAppUris(oidcClientMetadata))),
diff --git a/packages/core/src/routes/application.test.ts b/packages/core/src/routes/application.test.ts
index 9508beb00..c74ac6bd1 100644
--- a/packages/core/src/routes/application.test.ts
+++ b/packages/core/src/routes/application.test.ts
@@ -32,6 +32,7 @@ jest.mock('@/queries/application', () => ({
 jest.mock('@/utils/id', () => ({
   // eslint-disable-next-line unicorn/consistent-function-scoping
   buildIdGenerator: jest.fn(() => () => 'randomId'),
+  buildApplicationSecret: jest.fn(() => 'randomId'),
 }));
 
 const customClientMetadata = {
@@ -62,6 +63,7 @@ describe('application route', () => {
     expect(response.body).toEqual({
       ...mockApplication,
       id: 'randomId',
+      secret: 'randomId',
       name,
       description,
       type,
diff --git a/packages/core/src/routes/application.ts b/packages/core/src/routes/application.ts
index 762d9a13d..62f9e18ce 100644
--- a/packages/core/src/routes/application.ts
+++ b/packages/core/src/routes/application.ts
@@ -12,7 +12,7 @@ import {
   updateApplicationById,
   findTotalNumberOfApplications,
 } from '@/queries/application';
-import { buildIdGenerator } from '@/utils/id';
+import { buildApplicationSecret, buildIdGenerator } from '@/utils/id';
 
 import { AuthedRouter } from './types';
 
@@ -47,6 +47,7 @@ export default function applicationRoutes<T extends AuthedRouter>(router: T) {
 
       ctx.body = await insertApplication({
         id: applicationId(),
+        secret: buildApplicationSecret(),
         oidcClientMetadata: buildOidcClientMetadata(oidcClientMetadata),
         ...rest,
       });
diff --git a/packages/core/src/utils/id.ts b/packages/core/src/utils/id.ts
index 5072c37ee..c57dced5e 100644
--- a/packages/core/src/utils/id.ts
+++ b/packages/core/src/utils/id.ts
@@ -3,3 +3,5 @@ import { customAlphabet } from 'nanoid';
 export const alphabet = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
 
 export const buildIdGenerator = (size: number) => customAlphabet(alphabet, size);
+
+export const buildApplicationSecret = buildIdGenerator(64);
diff --git a/packages/schemas/src/seeds/application.ts b/packages/schemas/src/seeds/application.ts
index 28375affc..1caac5576 100644
--- a/packages/schemas/src/seeds/application.ts
+++ b/packages/schemas/src/seeds/application.ts
@@ -9,8 +9,9 @@ export const adminConsoleApplicationId = 'admin-console';
 
 export const demoAppApplicationId = 'demo-app';
 
-export const createDemoAppApplication = (): Readonly<CreateApplication> => ({
+export const createDemoAppApplication = (secret: string): Readonly<CreateApplication> => ({
   id: demoAppApplicationId,
+  secret,
   name: 'Demo App',
   description: 'Logto demo app.',
   type: ApplicationType.SPA,
diff --git a/packages/schemas/tables/applications.sql b/packages/schemas/tables/applications.sql
index e03613aa7..5de67a33f 100644
--- a/packages/schemas/tables/applications.sql
+++ b/packages/schemas/tables/applications.sql
@@ -3,6 +3,7 @@ create type application_type as enum ('Native', 'SPA', 'Traditional');
 create table applications (
   id varchar(21) not null,
   name varchar(256) not null,
+  secret varchar(64) not null,
   description text,
   type application_type not null,
   oidc_client_metadata jsonb /* @use OidcClientMetadata */ not null,