Slider CAPTCHA
Press the slider below and drag it right until the puzzle piece lines up with the gap, then release. The server validates the position and drag track, and the challenge works only once.
Press and drag the slider
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The gap's horizontal coordinate is never sent to the client; the server stores only a digest of the answer and compares candidates within the tolerance range on submit.
The drag track is validated: too few points, too short a duration, or instant jumps are rejected, so scripts cannot simply guess the position.
Each challenge can be verified only once; repeated failures trigger a short cooldown, and the endpoints are also rate-limited per IP.