Fastmail vs Zeplin

Fastmail (Open-source software developed at Fastmail.) and Zeplin both appear on the Smoower Developer Ecosystem Index.

Fastmail and Zeplin sit at essentially the same overall ecosystem score (40), which is unusual and worth reading through the pillars below.

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

Fastmail carries 6,316 GitHub stars across 38 public repos, with 12 repositories active in the last 90 days and 2 external contributors on record. Zeplin shows 1,460 stars across 57 public repos, 8 active in the last 90 days and 4 external contributors. The star gap on its own does not decide the comparison, but Fastmail's footprint is roughly 4.3x larger, which usually shows up in downstream signals like inbound issues and third party integrations.

Fastmail is the stronger read for anyone weighting reach. Zeplin looks better where code quality 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.