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Tech Tips, Tricks & Trivia

by 'Anil' Radhakrishna
An architect's notes, experiments, discoveries and annotated bookmarks.

Search from over a hundred HOW TO articles, Tips and Tricks


Lazy-Developer-CAPTCHA Text Extractor Bookmarklet

CAPTCHA or Completely Automated Public Turing Test To Tell Computers and Humans Apart, is a technique to to stop bots from signing up for online accounts or automatically filling up forms. The inventor of CAPTCHA is a computer science professor at Carnegie Mellon University named Luis von Ahn, who is also the brain behind Duolingo (the free language learning site/app) and considered the father of crowdsourcing. Google bought his company, reCAPTCHA, and uses our free labor to verify hundreds of millions of words from books that its scanners can’t parse.

The whole purpose of CAPTCHA is to prevent automation from the UI. The CAPTCHA image which includes the text within it (cannot be copied) is generated dynamically.

Some lazy developers choose to build a simpler implementation by overlaying dynamic text over a hazy background making it look like a CAPTCHA but as the text can be copied it defeats the purpose of having a CAPTCHA.


This Gist snippet for a JavaScript bookmarklet can be adapted to make filling a defective CAPTCHA easy.


[Update: 23/Sep/16] Yet another lazy developer of a custom CAPTCHA added a little twist to his CAPTCHA implementation by having spaces in the text to be typed -
The bookmarklet code can tackle that -



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