mockingtesting
API Mocking vs API Interception: What's the Difference?
API mocking replaces the API with a fake. API interception edits real traffic as it passes. See the difference with diagrams, and when to use each.
12 min
Blog
How-tos, tricks and field notes
Practical guides for seeing what your apps send, and for making them misbehave on purpose.
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debuggingai
Why developers still need a network interceptor in the AI era
AI-written code breaks at the network boundary. See how a network interceptor lets you edit API responses in transit, force errors and find bugs without touching the backend.
13 min
funtesting
Turn any API into a teapot: testing error handling with HTTP 418
Make a real server answer "I'm a teapot" on demand. A silly status code that's secretly the best way to find out whether your app copes with errors it has never heard of.
5 min
how-totesting
How to simulate a 502 from any API without touching the backend
Make a payment, login or search endpoint fail on demand, so you can see how your app handles errors. Two rules, no code changes, and one detail that keeps you from double-charging a card.
4 min
how-todebugging
Point a production app at your local server (without rebuilding anything)
Redirect requests from a deployed web app, desktop app or Postman to the API running on your laptop, using a single Modify Request rule and a template variable.
3 min
how-tomocking
Mock an API endpoint before the backend exists
Build the frontend first. Use a Modify Response rule to return realistic JSON for an endpoint that doesn't exist yet, including values pulled from the request URL.
4 min
how-tohttps
How to inspect HTTPS traffic from any app on your computer
A step-by-step guide to seeing the requests and responses your apps send, even over HTTPS, and how to read what you find.
4 min
how-totesting
Test timeouts, retries and slow networks on purpose
Make an endpoint hang, answer late, or fail after a delay, to check how your app behaves when the network is the problem rather than the server.
3 min
how-todebugging
Pause a request, edit it by hand, then send it
Use a Pause and Review rule to freeze matching requests before they leave your machine, change the method, URL, headers or body, and resume or drop them. A manual breakpoint for the network.
4 min
tipsrules
Seven rule tricks you'll use every day
Scope rules to one app, match several values at once, capture parts of a URL with regex, react to the response, and keep a library of rules you can switch on and off.
4 min
troubleshootinghttps
Why isn't my app's traffic showing up? A troubleshooting checklist
Work through the usual reasons a request doesn't appear in an intercepting proxy, from the system proxy and certificates to Node, Python, pinned certificates and localhost.
4 min