# Running Tests from the Web Tests that have been merged on GitHub are mirrored at [wpt.live](https://wpt.live) and [w3c-test.org](https://w3c-test.org). [On properly-configured systems](from-local-system), local files may also be served from the URL [http://web-platform.test](http://web-platform.test). Not all tests can be executed in-browser, as some tests rely on automation (e.g. via [testdriver.js](../writing-tests/testdriver)) that is not available when running a browser in a normal user session. ## Web test runner For running multiple tests inside a browser, there is a test runner located at `/tools/runner/index.html`. This allows all the tests, or those matching a specific prefix (e.g. all tests under `/dom/`) to be run. For testharness.js tests, the results will be automatically collected, while the runner provides a simple UI for manually comparing reftest rendering and running manual tests. Note, however, it does not currently handle more complex reftests with more than one reference involved. Because it runs entirely in-browser, this runner cannot deal with edge-cases like tests that cause the browser to crash or hang.