Free Mock REST & LLM API for Testing & Development
MockAPI Dog is a free, no-signup-required tool that lets you create and deploy mock REST APIs and LLM streaming endpoints instantly. Perfect for developers building applications that need quick API prototyping and AI integration testing.
How it works
Generate your endpoint
A unique short code is automatically generated for you
Configure your response
Select REST API with JSON or LLM streaming with AI-like responses
Deploy & use
Click save and your mock API is live immediately. Copy the URL and use it anywhere
Why use MockAPI Dog?
Instant setup
No registration, no API keys, no configuration files. Just open the page and start creating mock endpoints in seconds.
REST & LLM mocking
Create traditional REST APIs with JSON responses or mock LLM streaming endpoints compatible with OpenAI, Anthropic, and other providers.
Advanced testing
Simulate network delays, random failures, conditional errors, and LLM streaming behavior. Test how your app handles all conditions.
100% free
Completely free to use. No limits, no premium tiers, no credit card required.
Perfect for
- Frontend development: Build and test your UI without waiting for backend APIs
- AI/LLM integration: Test ChatGPT, Claude, or custom LLM integrations without burning through API credits
- API testing: Simulate different responses and error scenarios
- Rapid prototyping: Quickly validate ideas and demonstrate concepts
- Learning & education: Practice API integration without complex setup
- CI/CD testing: Use stable mock endpoints in your automated tests
Features
No signup required
No authentication or signup required - start building immediately
All HTTP methods
Support for all standard HTTP methods (GET, POST, PUT, DELETE, PATCH, HEAD, OPTIONS)
LLM streaming support
Mock OpenAI, Anthropic, and generic streaming formats with customizable token generation
Custom status codes
Custom HTTP status codes (200, 201, 400, 404, 500, and more)
JSON editor
Built-in JSON editor with syntax highlighting and validation
Delay simulation
Artificial delay simulation (test slow network conditions)
Error testing
Random error rate testing and conditional errors based on request headers
CORS enabled
CORS enabled for cross-origin requests from any domain
Common use cases
Testing AI chatbot integration
Build and test your AI chatbot UI with mock LLM responses before connecting to expensive production APIs. Save money during development.
Testing error handling
Create endpoints that return 404, 500, or other error status codes to test how your application handles failures.
Building without backend
Focus on frontend development while the backend is still being built. Replace mock endpoints with real ones later.
Workshop & training
Provide students with consistent, reliable API endpoints for learning exercises without infrastructure overhead.
Frequently Asked Questions
Do I need to create an account?
No! MockAPI Dog requires no signup or authentication. Just visit the site and start creating mock endpoints immediately.
Is it really free?
Yes, completely free with no hidden costs, premium tiers, or usage limits. We believe developers should have access to quality tools without barriers.
Can I use this for production?
MockAPI Dog is designed for development, testing, and prototyping. While endpoints are reliable, we recommend using production-grade APIs for live applications.
What LLM providers are supported?
We support OpenAI format (ChatGPT, GPT-4), Anthropic format (Claude), and generic streaming formats. The mock responses mimic the streaming behavior of these providers.
How long do endpoints stay active?
Endpoints remain active as long as they're being used. Inactive endpoints may be cleaned up periodically to maintain service quality.
Start building now
MockAPI Dog makes API development faster and easier. Whether you're building a prototype, testing edge cases, integrating AI features, or learning web development, get started in seconds with no barriers.
No installation. No configuration. No signup. Just code.