Tapmetry is a collection of tests for your device that run entirely in the browser: screen, touch, speakers, microphone, camera, keyboard, mouse, gamepad and refresh rate, plus tests of your reaction time, aim, typing speed and memory.
Why it exists
Checking a new phone for dead pixels or a second-hand laptop for a broken key should not require installing an app, creating an account or trusting a stranger with your webcam. Every test here uses standard web APIs that your browser already has. There is nothing to download and nothing to grant beyond the permission your browser asks for on the spot.
What "local" means here
Nothing you do on a test leaves your device. Colours are drawn by your browser, touch events are counted by your browser, audio and video streams are shown to you and thrown away. The site has no backend that could receive them. Apart from loading the page, the only network traffic is visit statistics, described in the privacy policy, and they never include anything from a test.
How the tests are written
Each test comes with a plain-language article: how it works, what the result means, what to do if something is wrong and when a device is a warranty case. The articles are written by hand and updated when readers ask questions. If a test cannot measure something precisely, it says so instead of pretending.
Who makes it
Tapmetry is built and maintained by an independent developer in Bulgaria. The site is supported by advertising placed below the test, never on it. Questions, corrections and ideas for new tests are welcome on the contact page.