This tool lets you store and share secret messages without having a special app to de-crypt them. Simply type in your message and a secret password. The generate button creates a data URI (a special link that contains data and doesn't point anywhere) containing your encrypted message and instructions to your browser on how to de-crypt it. you can bookmark that link or send it to a friend who can keep it hidden
The link will render on any JavaScript and DOM capable web browser* (including iPhones, androids, chrome-books, Linux machines (running Firefox or any webkit browser), Windows, OSX etc). This tool uses the RC4 algorithm (often used by Microsoft) and Will not protect you from technically inclined malefactors (it's intended to keep children and snoopy parents out). Note, This may be illegal for Iranian and Cuban nationals to use (and possibly more) because it may violate US arms export regulations. (but don't quote me on that, RC4 is fairly weak)
If you're interested in how it works, check out it's repo on Github or just use the "view source" command in your browser
*(except internet explorer (as usual), elinks probably wont work quite right either and almost certianly wont display images (also as usual))