mssgs makes its sticker check a free captcha for any website

Brummen, the Netherlands, 3 November 2026

mssgs, the independent Dutch group chat application, has made the human check its apps ask of every new account available to other websites. The sticker captcha, published at mssgs-stickers.com/captcha, lets any site put the same check on its own sign-up, contact or comment forms, free of charge and without cookies or tracking.

Instead of typing distorted letters or picking out traffic lights, a visitor taps the two matching stickers in a short animated set. A person is usually through in a couple of seconds.

Time, not a puzzle

Picture puzzles no longer hold software back: an AI agent can take a screenshot, recognise what is shown and click. The sticker captcha therefore does not depend on the puzzle being hard. Each set stands for 2.5 seconds once it has settled and is then replaced by a new one. A person sees the pair in about a second; an agent that captures the screen, reasons about it and clicks finds the set gone. The server keeps the time, not the page, and an answer given faster than anyone could look locks the visitor out.

Every set is drawn for that one check as a single animation. Each sticker in it is turned, scaled and moved by its own amount, starts at its own moment and has its caption cut off, so there is no separate image per sticker to compare and no text to read. A visitor can pass a site's check ten times an hour, which is enough for a person and far too few for a program collecting tokens, and browsers that report being driven by automation never pass.

One script and one server call

A site adds the check with one script and one element on its form, and nothing else loads until the visitor presses the box. When the visitor passes, a token travels with the form, and the site's server confirms it with a single call using its secret key. A token is valid once, for five minutes. The answer has the same shape as those of reCAPTCHA and Turnstile, so code written for either reads it as well.

Keys are issued on the spot, without an account. Each key can ask for a simple check of one round or a multi-round check of two to five rounds, in which every round hides the pair among look-alikes of a single character. The number of stickers per set, the theme and the domains on which the widget may run are set per key, and test keys are provided for automated test suites.

Nothing about the visitor is kept

The sticker captcha sets no cookies, carries no tracking or advertising and passes nothing to third parties. The visitor's IP address is used only to count attempts against abuse, held in memory for at most fifteen minutes, and sealed into the token so that the site can check that it matches; neither the site nor anyone else can read it from the token. The service runs on the same servers as mssgs, in the Netherlands.

Every sticker is a button that can be reached by keyboard, the widget announces the result of each pick, and the opening animation jumps instead of glides for visitors who ask their device for reduced motion. A timed picture check does not suit everyone, including people who cannot see the stickers or who need more time. For forms where that matters, a site can switch the time limit off or offer another way in.

Most captchas now ask people to do exactly the kind of work that software has become good at. We turned that around: spotting two matching stickers is easy for a person, and two and a half seconds is not enough for a machine to look, think and click. It already protects every new mssgs account, and other sites can now use it for free, without anyone being tracked.

René van Sweeden, founder of mssgs

Availability

The sticker captcha is available now at mssgs-stickers.com/captcha, free of charge with fair use. The same page offers a live demonstration, the documentation and code examples for curl, Node.js, PHP, Python and Go.

mssgs is free to use, carries no advertising, and hosts all data in the European Union. Downloads for every platform are available at mss.gs/en/downloads.