Key Chatter Tester is a free device test tool that runs entirely in your browser — detect keys that register twice. No upload, no account, no limits.
Check a keyboard for chatter — when one physical keypress registers two or more times. Click into the test box and type normally; if the same key fires again within the chatter threshold, it's flagged in red along with the exact gap.
The operating system's auto-repeat (which kicks in when you hold a key) is ignored, so only genuine sub-threshold re-fires are counted as chatter.
A worn or dirty switch bounces, so a single press is read as several presses. It shows up as doubled letters like 'thhe'.
No — held-key auto-repeat carries a repeat flag that the tester ignores. Only fresh, fast re-presses of the same key count.
Every calculation happens on this page, in your own browser. Your input is never sent to a server, never logged and never used for training — which also means the tool keeps working when you are offline.