This website lets you encode and decode messages with 5 different ciphers. The first three are Substitution Ciphers: ciphers which replace each unit of a message with a unit of ciphertext. Along with these substitution ciphers than can be easily implemented with pen and paper, we've included binary XOR, a simple cipher usually implemented with a computer.
Since substitution ciphers and binary XOR are easily broken, we've also provided you the option to encrypt your messages with AES Crypto, a much more secure encryption method.
Once you've encoded a message, you can opt to generate a QR Code of your ciphertext that you can scan with any QR reader.
If you want to learn more about any of these ciphers, you can check out the links above for explanations and demos. Happy encrypting!