Mock API & Data Generator

A complete client-side Mock API and synthetic data generator. Define custom field schemas or pick presets (Users, E-Commerce, Blog Posts, Subscriptions), simulate REST endpoints with latency and error status codes, and export server files for json-server, MSW (Mock Service Worker), Express.js, or in-memory fetch mocks.

How to Generate & Test Mock APIs

A Mock API Generator allows frontend developers, mobile engineers, and testers to create realistic REST API endpoints and datasets before backend services are ready.

1. Schema Definition & Data Generation

  • Custom Field Types: Define fields using generative types like Auto-increment IDs, UUID v4, Full Names, Emails, Phone Numbers, Price Ranges, Dates, Avatars, and Custom Enums.
  • Deterministic Seeding: Control data randomness using a seed integer so team members generate identical datasets across test runs.
  • Preset Schemas: Instantly initialize common data structures such as User Directories, E-Commerce Products, Blog Articles, or SaaS Subscriptions.

2. In-Browser Simulated Testing

  • Test endpoints directly in your browser with simulated HTTP verbs (GET, POST, PUT, DELETE).
  • Simulate custom HTTP response status codes (200 OK, 201 Created, 400 Bad Request, 404 Not Found, 500 Server Error).
  • Add artificial response latency (0ms to 1500ms) to test frontend loading spinners and UI skeleton states.
  • Test client-side search filtering (?search=term) and pagination (?page=1&limit=10).

3. Server & Code Export Options

  • json-server (db.json): Export schema compatible with npx json-server db.json for rapid local mock backend development.
  • MSW (Mock Service Worker): Generate ready-to-use handlers.ts for intercepting network requests in React, Vue, or Next.js applications.
  • Express.js Backend: Copy a complete, zero-dependency Node.js Express server script with CORS and memory CRUD endpoints.
  • In-Memory Client Fetch Mock: Get a clean client-side async helper function for prototype demos and offline development.

Frequently Asked Questions

Is my data saved on a remote server?

No. DevToolkit runs 100% in browser memory. All generated datasets, custom schemas, and server snippets remain private on your local device.

Can I filter or paginate generated data?

Yes. When testing GET endpoints in the interactive tester, search strings and pagination parameters dynamically filter and slice your generated dataset.

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