Checkbox and invisible captchas

After programs learned to read warped text, vendors stopped asking every visitor to type letters. The 2014 "I am not a robot" checkbox is the familiar example. You tick a box. Sometimes that is the whole test. Sometimes the page then asks you to select squares of a photograph: bicycles, traffic lights, bridges.

A later version can skip the puzzle. The page loads a script, the vendor scores the visit, and the site receives a pass or a number. The person may see nothing. These are called invisible or score-based captchas. hCaptcha and reCAPTCHA are products in this family. They are not the same as a PNG of six digits.

The check is no longer "does this string match the picture." The vendor uses signals from the browser session. There is often no image URL, no text field, and nothing to base64-encode. A screenshot of the widget includes the checkbox chrome and the rest of the page. That is not the input these models were built for.

Captcha OCR does not solve checkbox, photo-grid, or invisible captchas. What this API does not read lists that limit next to audio and Devanagari digits. If your page shows a picture of characters or a sum, you are in the older family, and the API guide applies. If it shows only a tick box, this service is the wrong tool.