Blowfish is a hashing function, created by Bruce Schneier in 1993, and was one of the first hashing algorithm to be open-source, and so widely used. The hashing key is very long (4kBytes !) and also random, which makes Blowfish encryption as of now really difficult to break. Actually the 16-iterations blowfish algorithm was never cracked. The versions of the algorithm using less iterations were attacked, but still remains very secure.
Blowfish is also a really fast function, except for the key creation part, as it uses very simple operations such as Xor. For now it seems really hard to decrypt Blowfish using traditionnal attacks such as bruteforce decryption or rainbow tables, that's why we only offer you ton Encrypt Blowfish using this online tool.