C.A.P.T.C.H.A.

C.A.P.T.C.H.A in use

Inspiration

The average person clicks 300 times a day without thinking. Mindless scrolling, accidental tabs, reflexive clicking through content you never actually wanted to see. I kept noticing how much of my own browsing was just autopilot. No intention, no awareness, just clicking.

I wanted to fix that.

What it does

C.A.P.T.C.H.A. is a Chrome extension that intercepts every left click and forces you to solve an inverse cognitive challenge before the click registers.

The prompt says select all even numbers. You have to click the odd ones. Select all vowels. You click the consonants.

Get it right and your click goes through. Fail 3 times and it lets you through anyway, because the extension believes in you. Eventually.

Trying to close the captcha? Clicking the X spawns a new one.

Every interaction is now a conscious choice.

The inverse mechanic specifically targets your prefrontal cortex, the part of your brain responsible for deliberate decision making. You cannot click on autopilot anymore.

How I built it

Chrome Extension Manifest V3 with a content script using capture-phase event listeners to intercept all trusted left click events before they reach the page. A DOM overlay renders at z-index: 2147483647 so it appears above everything on every website. After a correct solve or 3 failed attempts, the original click gets replayed via a synthetic MouseEvent dispatched to the original target element.

Vanilla JS
Chrome Extensions API (Manifest V3)
Zero dependencies
Zero backend

Challenges

The trickiest part was preventing the extension from intercepting its own synthetic replay clicks without creating an infinite loop. Solved with a suppression flag that deactivates interception for exactly one tick after the replay fires.

Accomplishments

It works on every website. Every click. No exceptions.

What I learned

Chrome extension architecture, capture-phase event interception, DOM injection, synthetic event dispatch, and that people will solve 3 inverse CAPTCHAs just to close a tab they accidentally opened.

Mindfulness works.