Mock APIs where mutations
actually persist
The modern JSONPlaceholder alternative. Perform real POST, PUT, and DELETE calls in an isolated visitor sandbox—without sign-up or polluting global data.
Try it live in one click
Select an endpoint preset below and hit send. Real responses, stateful mutations, and chaos edge cases at your fingertips.
{
"status": "success",
"data": [
{
"id": 1,
"user_id": 1,
"title": "sunt aut facere repellat provident occaecati excepturi optio",
"body": "quia et suscipit suscipit recusandae consequuntur expedita et cum reprehenderit molestiae ut ut quas totam...",
"created_at": "2025-08-15T10:00:00Z"
},
{
"id": 2,
"user_id": 1,
"title": "qui est esse",
"body": "est rerum tempore vitae sequi sint nihil reprehenderit dolor beatae ea dolores neque fugiat blanditiis...",
"created_at": "2025-08-15T10:05:00Z"
}
],
"meta": {
"page": 1,
"limit": 2,
"total": 100,
"total_pages": 50
}
}Built for modern developers who need real state
Move beyond stateless mock endpoints that reset every time your application reloads.
Stateless & Read-Only Mocks
Ideal for quick starter demos and simple read tests, but limited when prototyping full CRUD user interfaces or end-to-end test flows.
- –Simulated mutations: POST and PUT requests return echo IDs, but records are not saved to a persistent store.
- –Ephemeral session state: Data disappears on page reload, making complex multi-step UI flows tricky to test.
- –Shared baseline: All visitors see static read-only records without private per-user or per-test sandboxing.
- –Limited protocols: Primarily restricted to basic REST without integrated GraphQL gateway or payment flows.
Virtual Session Overlay
Execute full CRUD mutations that persist in your private visitor sandbox across reloads, without modifying shared database baselines.
- ✓Real persistent CRUD: Created items appear at the top of your lists; updates apply in-place; deletes vanish.
- ✓Zero-login isolation: Automatic HMAC-signed session cookie or header isolates your mutations privately.
- ✓State management controls: Export your sandbox snapshot to JSON, import it anytime, or click reset to baseline.
- ✓Full developer suite: GraphQL gateway, Stripe checkout simulation, virtual OTP email inbox, and chaos delay.
How stateful sandboxing works
A zero-configuration virtual layer powered by PostgreSQL and Express.
Automatic Visitor Session
The moment you or your test runner calls the API, an HMAC-SHA256 session token is assigned via an HTTP-only cookie or request header. No accounts, API keys, or sign-ups.
Virtual Mutation Overlay
Any POST, PUT, or DELETE request saves directly to your isolated session records. The global baseline database is never permanently modified or polluted.
Smart Merged Responses
All GET operations slice and merge the baseline with your mutations: created records appear at the top, updates reflect in-place, and deletes are filtered out.
Everything your frontend needs to build and ship
A comprehensive suite of mock backend services designed specifically for frontend engineers.
Zero-Login Session Sandbox
Perform real POST, PUT, and DELETE calls that persist in your private visitor sandbox across browser tabs and reloads.
Relational Sub-Resources
Query nested relationships such as /users/1/posts and /posts/1/comments with full-text search (?q=) and multi-field sorting.
Unified GraphQL Gateway
Run queries and mutations at /api/v1/graphql. Supports field selection, nested sub-queries, and schema introspection out of the box.
Latency & Error Simulation
Test frontend loading skeletons and error boundaries with parameters like ?_delay=1500 (0–20s) and ?_status=500 (400–599).
Mock JWT Auth & RBAC
Simulate real login and registration workflows with access tokens, refresh tokens, /auth/me profile, and role-based guards.
Virtual Email & SMS Inbox
Receive simulated signup verification emails and SMS OTP codes in a live virtual inbox to test end-to-end user onboarding.
Stripe Payment Simulation
Create checkout sessions, test card charges, simulate webhook confirmations, and manage mock customer payment methods.
SSE Streaming & WebSockets
Connect to Server-Sent Events (SSE) at /api/v1/stream and live WebSockets to prototype real-time feeds, chats, and live alerts.
One-click collections & SDK specs
Import Playground API directly into your favorite API client or TypeScript project.
OpenAPI 3.0 Specification
Import full endpoint contracts into Swagger UI, Redoc, or API code generators.
Postman Collection
Pre-configured collection with mock variables, test scripts, and bearer tokens.
Bruno Collection
Git-friendly, fast offline API client collection ready for your team repository.
Insomnia Collection
Full request workspace ready for one-click import into Insomnia Rest Client.
TypeScript Type Declarations
Strongly-typed interfaces for Users, Posts, Comments, Todos, and Auth responses.
Stop Waiting for the Backend
In-depth technical articles explaining Playground API features, stateful architectures, WebSockets, payment intents, and frontend autonomy.
React CRUD Without a Backend: Build Real Apps Today
Build a complete production-grade React CRUD interface with optimistic UI updates and persistent state overlays without running any local database.
Why Static Mock APIs Aren't Enough for Frontend Dev
Explore why traditional read-only mock servers fail during integration tests, and how stateful copy-on-write session sandboxes bridge the gap.
Mock APIs That Remember POST Requests
How to test real authentication loops, multi-step checkout forms, and user profiles with mock APIs that persist mutations per browser session.
Frequently asked questions
Everything you need to know about the sandbox without digging through pages of text.
Start building your frontend
with real state today
No registration, no API keys, and no database setup required. Instant endpoints ready for React, Next.js, Vue, mobile apps, and QA test suites.