Playground API is an instant, stateful mock REST and GraphQL backend designed for modern frontend, mobile, and AI development. It gives you realistic backend capabilities—with persistent mutations, auth flows, WebSockets, and fault injection—without writing backend code or managing databases.
Requests from your browser automatically receive a signed visitor session cookie (pg_identity). For server-side rendering, CI runners, or mobile apps, pass an X-Playground-Identity header.
For years, frontend and mobile engineers have had to choose between two frustrating extremes: static dummy APIs where POST requests vanish instantly, or heavy local backend setups requiring Docker, migrations, and seed scripts. Playground API bridges this gap with virtual session overlays.
POST /posts returns a fake ID, but subsequent GET queries never show your new record.Open your terminal and run these commands right now. No sign-up, no API key, and no configuration required.
Everything modern product teams need to prototype, test, and ship complete frontend applications.
POST, PUT, PATCH, and DELETE operations persist across browser reloads in your private visitor sandbox overlay.
Users, Posts, Comments, and Todos pre-populated with relational nested routing (/users/1/posts, /posts/1/comments).
Native WebSocket chat hub (/ws), Socket.io gateway, Server-Sent Events (SSE), and automated presence echo bots.
Register, login, token refresh rotation with concurrency mutex locks, and simulated 403 role-based permissions.
Hosted checkout sessions, payment intents, test credit card vaults, and interactive 3D Secure verification modals.
Integrated virtual email mailbox (Mailtrap-style) and SMS terminal for verifying OTPs and password reset links.
Configurable artificial latency (0-5000ms), jitter simulation, custom HTTP error status codes, and 429 rate limiting.
Define arbitrary custom schemas on the fly for dynamic E-Commerce, CRM, and SaaS database collections.
Full GraphQL gateway with schema introspection, nested relational queries, mutations, and realtime subscriptions.
Headless testing support with X-Playground-Identity headers to isolate parallel test runners in Playwright and Cypress.
Ready-to-use LLM context rules including llms.txt, llms-full.txt, product.json, and Cursor/Windsurf rule templates.
In-browser visual API workbench to inspect headers, execute live mutations, monitor payloads, and reset sandboxes.
Select a pathway to start integrating Playground API into your workflow.