> but if every site had their own in-house tool
Costs money to maintain and build correctly, which naturally leads to buying existing solutions.
Costs money to maintain and build correctly, which naturally leads to buying existing solutions.
I found a few starter ideas [1][2] and concepts [3] but I would prefer to use something like figlet vs gd generated images. Figlet or something like it should be much lighter weight. I just have to find one that is readable on cell phones.
[1] - https://github.com/lua-programming/lua-captcha
And sure, qntm.org isn't nearly as big a website as HN, but I concur that this isn't likely to be super-difficult. The wide use of recaptcha seems like mostly laziness; most websites aren't big enough to get targeted attacks.