Why sites use captchas
2026-01-09 · Captchas
A captcha makes a repeated form post cost an extra step, so a plain loop stops being free.
A public form can be called all night by a script: record search, slot booking, OTP request. A captcha adds a picture that changes every time, so replaying yesterday's answer fails.
It is a speed bump, not a login. The site still needs its own rate limits and accounts. The captcha only checks that this submission saw the current image.
When Captcha OCR returns reliable: false, do not type the text and do not send the same bytes again. The model will say the same thing. Refresh the portal image and solve the new one.
If you run your own site, put the captcha on the few routes that are abused, not on every click. People abandon forms that ask twice.
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