Steins;Gate originally was a visual novel, the anime adaption was created later by
Funimation and studio White Fox in collaboration with
Nitroplus. It consists of 24 episodes and
also has a
special 25th episode which is set after the original series.
As an introduction to Steins;Gate 0, an alternate ending to episode 23 has been released. Episode 23 β was translated by WhyNotSubs and can also be viewed on YouTube.