Argon2 is a password-hashing function created by by Alex Biryukov, Daniel Dinu, and Dmitry Khovratovich. Argon2 is in the public domain and can be downloaded from GitHub. Argon2 was declared the winner of the Password Hashing Competition (PHC). There were 24 submissions and 9 finalists. Catena, Lyra2, Makwa and yescrypt were given special recognition. The PHC recommends using Argon2 rather than legacy algorithms.

There are two versions of Argon2. Argon2d provides the highest resistance against GPU cracking attacks. Argon2i is designed to resist side-channel attacks.