Calendly vs Fastmail

Calendly (Simple, beautiful scheduling.) and Fastmail (Open-source software developed at Fastmail.) both appear on the Smoower Developer Ecosystem Index.

Fastmail (rank #432) holds a modest lead over Calendly (rank #729) on the overall Smoower ecosystem score (40 vs 30). The gap of 10 points reflects composite signals across code, docs, community and reach.

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

Calendly carries 132 GitHub stars across 29 public repos, with 0 repositories active in the last 90 days and 0 external contributors on record. Fastmail shows 6,317 stars across 38 public repos, 12 active in the last 90 days and 3 external contributors. The star gap on its own does not decide the comparison, but Fastmail's footprint is roughly 47.9x larger, which usually shows up in downstream signals like inbound issues and third party integrations.

Calendly is worth a look for teams already invested in its stack. Fastmail looks better where momentum 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.