These crypto-tools are inspired by Dan Boneh's crypto 1 class. (View it on Coursera)
They are written in javascript and are available for education and fun. I wouldn't recommend using them for real-world cryptographic purposes, but you can #DoWhatchaWant. Here are some security considerations about javacsript-based crypto. I think these tools are exempt because they are 100% client-side, but it's still an interesting read.