Fastmail vs MailerSend

Fastmail (Open-source software developed at Fastmail.) and MailerSend (Email service that delivers) both appear on the Smoower Developer Ecosystem Index.

MailerSend (rank #401) holds a narrow lead over Fastmail (rank #430) on the overall Smoower ecosystem score (41 vs 40). The gap of 1 points reflects composite signals across code, docs, community and reach.

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

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. MailerSend shows 499 stars across 22 public repos, 12 active in the last 90 days and 7 external contributors. The star gap on its own does not decide the comparison, but Fastmail's footprint is roughly 12.7x larger, which usually shows up in downstream signals like inbound issues and third party integrations.

Fastmail is the stronger read for anyone weighting reach. MailerSend looks better where education 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.