Crypt.re

This free service allows you to encrypt rich text data in a safe way. Choose a strong passphrase (or just click generate button) and it will take over the age of universe to brute-force attack your data. I use Advanced Encryption Standard (AES-256), approved by the National Security Agency (NSA) for top secret information.

When you click encrypt button, your data is immediately encrypted via JavaScript and then saved in the database. I do not store clear data, I do not store your passphrase. So I am not able to decrypt your data, nor anyone else. Even if a governmental authority wanted to seize my database, it would be totally unworkable as the encryption is high.

Unless you choose a stupid passphrase like 12345, the sun should stop burning before your data was decrypted.
Please, check the FAQ for more infos.