Free, Stateful Mock REST & GraphQL Backend for Frontend Prototypes
Build real CRUD applications with working JWT authentication, dynamic custom tables, and network latency simulation — with zero database or server configuration.
Traditional Mock APIs Fake It. Playground API Saves It.
Why building realistic frontend prototypes with legacy mock backends always falls short — and how our per-visitor sandbox fixes it.
Returns fake object: { id: 101, title: 'New Post' }
Your newly created post is nowhere to be found. The server never stored it.
- Mutations vanish on subsequent requests and page reloads.
- Cannot test real CRUD interfaces, shopping carts, or task lists.
- No working JWT auth loops or protected endpoints.
Persists into your private session overlay: { id: 101, ... }
Your post appears at the top of the list across page refreshes and components.
- Full CRUD persistence (POST, PUT, PATCH, DELETE) in your private session.
- Zero sign-up or database setup — automatic browser session isolation.
- Full JWT auth, custom collections, network delay headers, and snapshot exports.
How It Works in 3 Simple Steps
Get a production-grade mock backend for your frontend development in under 10 seconds.
Point Your API Client
Swap your API base URL to our public endpoint in your React, Vue, Next.js, or mobile app. No registration, API keys, or database setup required.
const API_URL = 'https://playground-api-xi.vercel.app/api/v1';
const posts = await fetch(`${API_URL}/posts`);Automatic Isolated Sandbox
Every visitor automatically gets a secure session identity. Your created posts, updated profiles, and deleted items persist privately in your browser without altering global baseline data.
// All CRUD operations persist in your private overlay
await fetch('/api/v1/posts', {
method: 'POST',
body: JSON.stringify({ title: 'My Item' })
});Simulate Edge Cases & Export
Test loading skeletons with ?_delay=1500, verify error boundaries with ?_status=500, authenticate with fake JWT Bearer tokens, or export your full sandbox snapshot as JSON.
// Simulate slow 3G network latency
fetch('/api/v1/posts?_delay=1500');
// Or simulate a 500 error boundary
fetch('/api/v1/posts?_status=500');Built for Every Stage of Frontend Development
From single-page portfolio projects to automated CI/CD pipelines and interactive programming classrooms.
Portfolio & Interview Take-Home Apps
Build real eCommerce stores, Kanban boards, or social feeds that recruiters and interviewers can actually test live. Items added by the user stay in their browser without a real database.
- Persistent cart items & task updates
- Working JWT login/register flows
- Custom collection schemas on the fly
Automated E2E & Component Testing
Run deterministic Playwright, Cypress, or Jest suites without spinning up Docker or cloud staging databases. Test slow network spinners and 500 error boundary fallbacks reliably.
- Deterministic test runs with X-Playground-Identity
- Latency simulation with X-Simulate-Delay
- Instant test teardown with DELETE /session/reset
AI Coding Agents & Prompt Sandboxes
Feed our structured /llms.txt documentation into Cursor, Claude, ChatGPT, or GitHub Copilot to let AI agents build complete, working web apps connected to persistent mock APIs.
- Machine-readable schema at /llms.txt
- Zero API keys or auth hurdles for AI agents
- TypeScript definitions via /public/types/ts
Classrooms, Bootcamps & Workshops
Teach React, Vue, Svelte, or Flutter to hundreds of students simultaneously. Because each student gets an isolated browser sandbox, they never overwrite or delete each other’s records.
- No student database setup or SQL headaches
- Multi-format collections for Postman & Bruno
- Unified REST and GraphQL endpoints
Engineered for Real-World Prototyping
Everything frontend developers, QA suites, and AI model agents need to prototype, test, and ship applications without managing servers.
Complete CRUD with State Persistence
Perform real POST, PUT, PATCH, and DELETE operations. Your mutations persist across page refreshes in your private session overlay.
Network Delay & Error Simulation
Simulate slow 3G networks or 500 error boundaries on demand with simple headers like X-Simulate-Delay: 1500 or ?_status=500.
JWT Authentication Simulation
Simulate full authentication loops with /auth/login, /auth/refresh, and protected Bearer token profile endpoints.
Dynamic Custom Collections
Create arbitrary collections on the fly like /custom/products or /custom/orders without touching backend code or database schemas.
Unified REST & GraphQL Gateway
Query standard REST endpoints under /api/v1 or execute GraphQL queries and mutations against /api/v1/graphql with GraphiQL IDE.
Snapshot Export & Import
Export your entire sandboxed mock database as a JSON file to share with teammates or load into automated Playwright test runs.
Deterministic SVG Avatar Generator
Generate crisp vector SVG user avatars and landscape thumbnail placeholders dynamically with /api/v1/avatars/:seed.
Universal Full-Text Search
Filter dataset records instantly across titles and bodies using the full-text search parameter ?q=keyword.
Postman, Bruno & OpenAPI 3.0 Specs
Download ready-to-use workspace collections for Postman, Bruno, Insomnia, Swagger OpenAPI, and TypeScript .d.ts definitions.
How Playground API Compares to Alternatives
See why developers choose Playground API over legacy mock APIs for real-world prototyping.
| Feature / Capability | Playground API | JSONPlaceholder | Platzi Fake API | DummyJSON |
|---|---|---|---|---|
| Persistent Per-Session Mutation Overlays | Real Virtual State | ❌ Fake Payload Echo | ❌ Fake Payload Echo | ❌ Fake Payload Echo |
| GraphQL Gateway Support | Yes (/graphql) | ❌ No | ✅ Yes | ❌ No |
| Fake JWT Auth Simulation | Full Bearer Auth | ❌ No | ✅ Yes | ✅ Yes |
| Dynamic Custom Collections | Yes (/custom/*) | ❌ No | ❌ No | ❌ No |
| Network Delay & Error Headers | Headers & Params | ❌ No | ❌ No | ⚠️ Limited |
| Session Snapshot Export / Import | Portable JSON | ❌ No | ❌ No | ❌ No |
| Relational Sub-Resource Filtering | Full Support | ✅ Basic | ❌ No | ✅ Basic |
| AI Readable (/llms.txt) Specification | Yes | ❌ No | ❌ No | ❌ No |
| One-Click Multi-Format Spec Downloads | 5+ Formats | ❌ No | ❌ No | ❌ No |
Quickstart Integration Snippets
Copy and paste integration code in Fetch, Axios, Python, Go, Swift, Rust, or cURL.
Explore Built-in Mock Datasets
Ready-to-use resources with full pagination, filtering, full-text search, and relational support.
Users
User profile records with names, usernames, emails, address details, and avatar seeds.
Posts
Blog post articles containing title, body, user association, created dates, and full-text search indexing.
Comments
Feedback comments linked relationally to blog posts.
Todos
Task item records with completion status.
Authentication
Fake JWT authentication login, user registration, token refresh, and profile inspection.
Custom Collections
Dynamic custom resource collections (e.g. /custom/products, /custom/orders) created on the fly.
Media & Avatars
Dynamic SVG avatar vectors and landscape image thumbnail generators with deterministic gradient backgrounds.
Session Sandbox
Export, import, and reset operations for identity session overlays.
Frequently Asked Questions
Everything you need to know about Playground API architecture and integration.