Comment by piotrkaminski

Sorry, not going to happen as things stand. A big part of Reviewable's attraction is the tight GitHub integration, so supporting other platforms (BitBucket, GitLab) would essentially require a fork or some pretty heavy-duty abstractions. Either way, future maintenance would become much harder, so I can't build a business case for it. Perhaps if BitBucket or GitLab were larger / growing faster, or if Reviewable was a much larger company with many developers to throw at the problem...