37signals vs Fastmail

37signals (HEY! It's in Basecamp!) and Fastmail (Open-source software developed at Fastmail.) both appear on the Smoower Developer Ecosystem Index.

37signals (rank #122) holds a modest lead over Fastmail (rank #430) on the overall Smoower ecosystem score (54 vs 40). The gap of 14 points reflects composite signals across code, docs, community and reach.

On code quality (the state of repositories, tests, releases and polish), 37signals is clearly ahead of Fastmail. On education (docs, guides and learning material for developers), Fastmail is ahead of 37signals. On community (issue response, PR reviews and discussion health), 37signals is clearly ahead of Fastmail. On reach (how visible the ecosystem is beyond its own repos), Fastmail is clearly ahead of 37signals. On momentum (release cadence and how fast the ecosystem moves), 37signals is slightly ahead of Fastmail.

37signals carries 113,857 GitHub stars across 236 public repos, with 48 repositories active in the last 90 days and 298 external contributors on record. Fastmail shows 6,316 stars across 38 public repos, 12 active in the last 90 days and 2 external contributors. The star gap on its own does not decide the comparison, but 37signals's footprint is roughly 18.0x larger, which usually shows up in downstream signals like inbound issues and third party integrations.

37signals is the stronger read for anyone weighting code quality. Fastmail looks better where reach is the deciding factor. The table below breaks the scores down pillar by pillar; the linked profiles cover the underlying repos, docs and community signals in full.