Mock API responses instantly. Intercept HTTP requests and return custom responses for testing and development.
Users
3
−1 in 30 days
Rating
0.0 / 5
unchanged in 30 days
Ratings
0
0 in 30 days
Store rank
#336K
#261K among extensions
Version
2.0.0
updated 13 Jun 2026
Users
monthly, 5 months
Latest, 15 Oct 2026:3 usersMove the mouse over the chart for any month
Ratings count
monthly, 5 months
Latest, 15 Oct 2026:0 ratingsMove the mouse over the chart for any month
The Chrome Web Store rounds user counts down to the leading digit, so the user line moves in steps. The ratings count is exact and is the better signal of real adoption.
About MockMaster
MockMaster - The only API Mocker you'll need
Want to test multiple API response scenarios without making any backend changes?
Want to unblock yourself from annoying CORS error?
Need to create a demo showcasing various scenarios?
MockMaster is the answer. Mock any API (GET/POST/PUT/PATCH/DELETE) to return any kind of response (Success/Failure/whatever you want).
A simple UI to create/update/delete the mocks and to enable/disable them.
No data is collected. Everything happens locally on your machine.
Mock API responses instantly with the most intuitive and powerful API mocking extension for Chrome. Perfect for frontend development, testing, and demos.
KEY FEATURES
• Instant API Mocking - Intercept and mock any HTTP request (GET, POST, PUT, DELETE, PATCH)
• Flexible URL Matching - Support for full URLs, pathnames, and powerful regex patterns
• Custom Responses - Set any status code (200, 404, 500, etc.) and response body
• JSON & Text Support - Full support for JSON responses and plain text
• One-Click Toggle - Enable or disable rules instantly without deleting them
• Visual Indicators - Color-coded HTTP methods and status codes for easy identification
• Local Storage - All your mock rules are stored securely in your browser only
• Zero Configuration - Install and start mocking immediately, no setup required
HOW IT WORKS
1. Click the extension icon to open the beautiful popup
2. Click "Add Rule" to create a new mock
3. Enter your URL pattern (e.g., /api/users or https://api.example.com/.*)
4. Select HTTP method (GET, POST, PUT, DELETE, PATCH)
5. Set response status code (200, 404, 500, etc.)
6. Add your response body (JSON or plain text)
7. Toggle the rule on/off as needed
8. Browse any website - matching requests are automatically mocked!
📝 URL PATTERN EXAMPLES
Full URL: https://api.example.com/users
Pathname: /api/users
Regex Pattern: /api/users/.*
Simple Pattern: example.com
⚡ Install MockMaster today and transform your development workflow!
Perfect for teams and individual developers who value beautiful tools that just work.