Test the API where you can already see it
Every request your web app makes already passes through the browser. These extensions use that traffic directly instead of making you retype endpoints, headers and payloads into a separate client. They're for backend and QA engineers who need API regression coverage, frontend developers who need to fake a response the backend can't produce yet, and anyone who has lost an afternoon to a field that quietly changed type.
Which one should I use?
- Generating API tests from how the app really behaves — XHRScribe records live XHR and fetch calls and turns them into runnable tests with payloads, headers and assertions.
- Generating integration tests from your code — APItiser reads your API endpoints and produces integration tests with request setup and assertions.
- Mocking, holding or rewriting a response — Mockingbird arms a single tab, lets you set breakpoints on requests and mock any endpoint with your own status, headers, body and latency. It needs no proxy certificates and no backend.
- Catching breaking API changes early — Telltale learns each endpoint's schema from the responses it sees and alerts you when a field goes missing, a type changes or an unexpected null appears.
Traffic-based vs code-based tests
XHRScribe and APItiser both produce API tests, but they start from different places. XHRScribe starts from observed traffic, so its tests reflect real URLs, headers and bodies. That makes it the quicker option when you can click through the feature. APItiser starts from the code, so it can cover endpoints the UI never calls. Many teams use both: traffic-based tests for the flows users take, code-based tests for the rest of the API.
How they fit together
Use Telltale while you browse during development, so drift shows up the moment it happens rather than in a failing UI later. When you need to see how the frontend handles an error, a slow response or an empty list, Mockingbird can return that response without anyone changing the server. Once the behaviour is right, capture it with XHRScribe or APItiser so it stays covered. The guide to mocking API responses in Chrome without a proxy compares Mockingbird with the other options.
For the UI side of the same workflow, see the QA testing extensions. For designing the negative cases your API tests should include, see how to write negative and edge-case test cases.
More collections: QA testing extensions · AI developer tools · all extensions
