# Playground API — AI Model Documentation & Overview

> Free, Instant, Sandboxed Mock REST & GraphQL API Service for Web & Mobile Development.
> Base API URL: /api/v1
> OpenAPI Spec: /api/v1/downloads/openapi.json
> Postman Collection: /api/v1/downloads/postman.json
> TypeScript SDK: /api/v1/downloads/playground-api.d.ts

## Project Overview
Playground API is a modern JSONPlaceholder & Platzi Fake API replacement engineered with identity-isolated mutation overlays over global seed datasets. Frontend applications can perform real POST, PUT, PATCH, and DELETE operations without requiring database setup or backend code.

## Key Features for AI Developers & Agents
1. **Sandboxed Overlay State**: User mutations (creates, updates, deletes) are isolated per visitor using signed tokens (`pg_identity` cookie or `X-Playground-Identity` header).
2. **Global Seed Dataset**: Shared read-only base data for Posts (100 items), Comments (500 items), Users (10 items), Todos (200 items).
3. **REST & GraphQL Gateway**: Complete REST endpoints under `/api/v1` plus a GraphQL Gateway at `/api/v1/graphql`.
4. **JWT Authentication Simulation**: POST `/auth/login` and GET `/auth/me` for prototyping auth flows.
5. **Dynamic Custom Resources**: Arbitrary collection paths like `/custom/products` or `/custom/orders`.
6. **Network Simulation Headers**: Support for `X-Simulate-Delay: 1000` and `X-Simulate-Status: 500` middleware testing.

## Core API Endpoints Reference
- GET /api/v1/posts (List posts, supports ?page=1&limit=10&q=search&_sort=title&_order=desc)
- GET /api/v1/posts/:id (Get post by ID or local sandbox ID)
- POST /api/v1/posts (Create new post overlay)
- PUT /api/v1/posts/:id (Replace post overlay)
- PATCH /api/v1/posts/:id (Partial post overlay update)
- DELETE /api/v1/posts/:id (Delete post overlay)
- GET /api/v1/users (List users)
- GET /api/v1/users/:id/posts (Relational user posts)
- POST /api/v1/auth/login (Fake JWT login)
- GET /api/v1/auth/me (Get profile via Bearer token)
- POST /api/v1/graphql (GraphQL query & mutation gateway)

## How to Integrate in Real-World Projects
```javascript
// Fetch posts using standard JavaScript fetch
const response = await fetch('/api/v1/posts?_limit=5');
const posts = await response.json();
console.log('Fetched posts:', posts);
```

Full specification available at: https://playground-api-xi.vercel.app/llms-full.txt