Kr!pt is a simple encryption/decryption tool in JavaScript, so that it can be run on any device with a browser; it is more of a toy. Kr!pt is written by István Zsolt Berta, its source code is available under GPL.
Kr!pt does not come with any warranty; in particular, if you lose your passphrase you may lose access to all the data you encrypted with that passphrase.
Kr!pt uses the CryptoJS, it is a separate package and comes with its own license.