48.3k stars · MIT · v6.2.0 (2026-03-01)
The MIT community fork of Cal.com after the company went closed source — a booking link for user interviews and demos.
▶Repo detailsthe review · specs · pros & cons · install
What it is
A self-hosted scheduling platform — the open-source answer to Calendly — where you publish a link, someone picks a slot, and it writes the meeting into your calendar and sends the invitations. As of this year it is the community fork: Cal.com the company moved its product to closed source, and cal.diy is what remains, 100% MIT with the enterprise code stripped out.
Why it matters
The thing a solo founder before product-market fit needs most is conversations with the handful of people who did show up, and the thing that kills those conversations is six emails about time zones. A booking link at the bottom of every video description, every comment reply and every email turns "we should talk sometime" into a slot in your calendar. It is also, unglamorously, how you get testimonials and case studies — you cannot write one about a user you have never spoken to. Read the second half of this entry carefully though, because the licence story here is the most instructive thing on today's page.
- Fully MIT with no enterprise tier held back — which is more than can be said for half of what this radar has recommended you
- Enormous accumulated feature set: buffers, time zones, round-robin, payments, calendar sync in both directions
- A booking page costs you nothing to publish and starts working the day you paste the link somewhere
- The company behind it has walked away. A fork with the commercial code removed is only as alive as the volunteers who pick it up; the most recent tagged release is v6.2.0 from 1 March 2026. Treat it as a tool you use, not a dependency you build on
- Self-hosting it is a heavy Next.js stack plus its own database plus Google/Microsoft calendar OAuth plus an SMTP provider. This is not an evening
- Cal.com's own hosted free tier still exists and is genuinely the sensible starting point — the self-host is a project, and you do not need a project to get a booking link
Start with the hosted free tier: no VPS cost, no code, a link you paste into your YouTube descriptions and your Starlight docs footer today.