Keccak 256 bit Hash Generator
Keccak is the winner of SHA-3 competition, so many people referring SHA-3 as Keccak. The core algorithm is still the same, but there's slight modification for SHA-3. That's why when we compared the result of SHA-3 with Keccak result, it will be different.
Fun fact: if you try to learn keccak algorithm, you may encounter word absorb and squeeze which related with Sponge.
Keccak use Sponge construction, not Merke-Damgård construction which used on MD4, MD5, RIPE-MD, RIPE-MD160, SHA0, SHA1, SHA2.