head to head · open source
Cal.com vs appointment
Cal.com has 48,529 GitHub stars, 15,154 forks, 1,432 open issues and last shipped 4 days ago. appointment has 552 stars, 29 forks, 186 open issues and last shipped 2 days ago. Cal.com leads on adoption by 8,691% (48,529 vs 552 stars). Cal.com is written in TypeScript under MIT; appointment is written in Python under MPL-2.0. Cal.com has attracted 31% as many forks as stars, appointment 5%. appointment was the more recently maintained of the two, and both are self-hostable with no licence fee.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
← all 8884 open source comparisons
Side by side
| Cal.com | appointment | |
|---|---|---|
| GitHub stars | ★ 49K | ★ 552 |
| License | MIT | MPL-2.0 |
| Written in | TypeScript | Python |
| Last push | 2026-09-14 | 2026-09-16 |
| Forks | ⑂ 15K | ⑂ 29 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Cal.com if
- You weight community size — 49K stars and counting
- You want the MIT license terms
- Your stack matches TypeScript
- You value the larger contributor base for long-term maintenance
pick appointment if
- You want the appointment feature set and don't need the biggest community
- You prefer the MPL-2.0 license terms
- Your stack matches Python
- You evaluated both and appointment fits your workflow better
About Cal.com
Cal.diy is a fully open source, community maintained fork of Cal.com, stripped of all enterprise and commercial features. It provides a self hosted scheduling platform built on the T3 stack (Next.js, tRPC, Prisma, Tailwind CSS, Zod), licensed under MIT with no proprietary code or license keys required.
read the full Cal.com overview →
About appointment
Thunderbird Appointment is a self hostable, MPL 2.0 licensed scheduling application from the Thunderbird project that lets someone publish their availability and invite others to book open times on their calendar, and it is aimed at individuals, teams and organisations that want a booking link workflow running on infrastructure they control.
read the full appointment overview →
More in Business Software
Related comparisons
More Scheduling & Event Management projects
Compare either of these against the rest of the Scheduling & Event Management field.
Frequently asked questions
Is Cal.com or appointment more popular?
Cal.com has 48,529 GitHub stars and appointment has 552. Cal.com has the larger community by that measure.
Are Cal.com and appointment free?
Both are open source. Cal.com is licensed under MIT and appointment under MPL-2.0. Neither carries a licence fee.
What is the difference between Cal.com and appointment?
Cal.com is written in TypeScript and appointment in Python. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Cal.com or appointment?
Choose Cal.com if you want the larger community (48,529 stars) or its MIT licence terms. Choose appointment if its feature set, stack or MPL-2.0 licence fits better. Both are self-hostable.