“Does Tuesday work?” “Tuesday is out, how about Thursday?” Calendly turned that thread into a link, then into a seat price, and for a long time the open source answer to it was a single word: Cal.com. In April the word stopped being true.
The best open source Calendly alternatives you can still self-host are Cal.diy (MIT, the community fork of Cal.com), Easy!Appointments (GPL-3.0, free, built for service businesses) and Rallly (AGPL-3.0, free for up to three open polls, $6 a seat a month on its cloud, checked Oct 28, 2026). Tymeslot, Thunderbird Appointment and Calnode cover the gaps between them. Cal.com itself is no longer open source: its production code went private on April 14, 2026, and its hosted Teams plan costs $12 a user a month billed yearly.
Is Cal.com still open source?
Cal.com is not open source anymore, but Cal.diy, its MIT-licensed community edition, is. On April 14, 2026, Cal.com's Bailey Pumfleet wrote on the company blog: “After five years as open source champions, Cal.com is going closed source.” The reason given was security, with AI tools now able to scan a public codebase for vulnerabilities. The next day an engineering post confirmed that the production codebase had moved to a private repository and that the public one, calcom/cal.diy, would carry on as the self-hostable community version.
Cal.diy keeps the booking pages, event types, availability, the app store and the API, and it inherits the old repository's history and its roughly forty-nine thousand stars. What it loses is everything Cal.com sells to companies: Teams, Organizations, round-robin and collective events, Workflows, Routing Forms, SAML single sign-on and the Insights dashboard. There is no hosted version, and the README says Cal.diy is “strictly recommended for personal, non-production use.” For one person who wants a booking link on their own server, it is still the most complete free scheduler there is. For a sales team, it is not.
The open source twin did not disappear. It got split in two: the code you can own is now a hobby project, and the code companies pay for is behind a door.
The bill it cancels
A Calendly seat costs $10 a month on Standard and $16 a month on Teams, both billed yearly, and Enterprise starts at $15,000 a year for fifty seats (checked Oct 28, 2026 on calendly.com/pricing). Seats are for the people who host meetings; invitees do not need one. Those seats built a company last valued near three billion dollars, on a raise of around three hundred and fifty million in January 2021. The free plan is real but narrow: one event type and one calendar connection. The moment you want a fifteen-minute call and a thirty-minute call as separate links, you are on Standard.
Cal.com's own cloud is the honest comparison, because it is what Cal.com now asks you to use instead of Cal.diy. Individuals are free with unlimited event types and calendars, Teams is $12 a user a month billed yearly, and Organizations is $28 (checked Oct 28, 2026 on cal.com/pricing). None of that is unreasonable for software someone else runs and patches. The self-hosted route still exists too; it just runs through smaller projects than it used to.
The open source Calendly alternatives you can run today
Easy!Appointments is the one to look at first if you book clients rather than colleagues. It is GPL-3.0, written in PHP on MySQL, and version 1.6.1 shipped on October 19, 2026 (repo, about forty-five hundred stars). Its site calls it “free, open source appointment scheduling on your own server,” with providers, services, working hours and a public booking page built in. The maintainer also sells managed hosting at €20 a month billed annually, less than two Calendly seats.
Rallly solves the other half of the problem: finding a time a group can agree on, the job Doodle used to own. It is AGPL-3.0, with about fifty-three hundred stars and a release on October 26, 2026 (repo). Self-hosting is free. The hosted Hobby plan is free for up to three open polls with thirty-day retention, and Pro is $6 a seat a month billed yearly, which the pricing page calls an early-adopter rate that will go up (checked Oct 28, 2026). It is not a booking page, but for a committee or a hiring panel it is the right tool.
Tymeslot is the closest thing to a Cal.com replacement for one person or a small team: AGPL-3.0, written in Elixir, one container, with version 1.33.0 out on October 28, 2026 (repo, about two hundred seventy stars) and a managed cloud if you want one. Thunderbird Appointment comes from the people behind the Thunderbird mail client, is MPL-2.0 and sits on top of any CalDAV calendar you already run (repo, about five hundred fifty stars, updated October 28, 2026). Calnode is the smallest and most opinionated: a single Go binary with SQLite, Apache-2.0, described by its own README as a “lean, self-hostable Calendly & Cal.com alternative” (repo, about a hundred thirty stars, version 0.11.2 on October 27, 2026). It is not in our catalog yet and it is small, so treat it as a project to watch.
| Tool | Licence | Hosted price (Oct 28, 2026) | Best for |
|---|---|---|---|
| Cal.diy | MIT | none, self-host only | one person's booking link |
| Easy!Appointments | GPL-3.0 | €20 a month managed hosting | clients booking a service |
| Rallly | AGPL-3.0 | free, Pro $6 a seat a month | group polls |
| Tymeslot | AGPL-3.0 | managed cloud available | small-team booking pages |
| Thunderbird Appointment | MPL-2.0 | none, self-host | CalDAV users |
It is a wave, not one app
The AppClap catalog count shows the shape of it. Of the 573 scheduling tools live on AppClap (Oct 28, 2026), 41 are open source, 48 can be self-hosted and 305 have a free tier of some kind. Scheduling is a category where the free plan is the norm and the open source option is the exception, which is why Cal.com's move mattered: it took the one big exception off the board. What has grown back is five smaller projects, every one with a release in the last two weeks, and a community fork that still works. The category never collapsed into one vendor, and April is the reason it should not be allowed to.
What you actually take on
Calendly earns its seat price with the parts none of these projects have finished. Round-robin routing for a sales team, lead qualification forms, Salesforce lookups, SSO and an admin who can see every booking across the company are Teams and Enterprise features, and Cal.diy removed exactly those. If your scheduling is a revenue process rather than a convenience, the paid tools are selling something real.
Self-hosting a scheduler also means owning the calendar sync. OAuth credentials expire, APIs change, and a stale sync double-books a client. You will run a database, apply updates, and be the person who notices at 7am that the booking link is down. The honest middle for many small teams is a hosted plan from the maintainer: Cal.com's free individual plan, Rallly's $6 Pro, Easy!Appointments' €20 hosting. Open code you could leave with, run by someone whose job it is.
- 1Do you need one booking link for yourself, or a routed queue for a whole team?
- 2Is someone on your team comfortable keeping a server, a database and a calendar OAuth connection healthy?
- 3Does it bother you that the open source tool you picked can change its licence next spring?
- 4Are you paying for a second Calendly seat just to get a second event type?
Is Calendly free?
Calendly has a free plan, and it is limited to one event type and one calendar connection (checked Oct 28, 2026). That is enough for a freelancer with a single kind of call. Multiple event types, multiple calendars, reminders and payments start at $10 a seat a month billed yearly on Standard. Cal.com's free plan is wider, with unlimited event types and calendars for one user. Cal.diy, Easy!Appointments and Rallly are free to run on your own server with no seat count at all.
The series has been walking down a hallway of paid-app doors, from the dictation app to the deploy platform, the CRM, the login, the mailbox, the visitor book and the shop window. This door is the appointment book on the front desk, and the twist is that the free twin behind it changed its mind halfway through the year. We keep writing these at AppClap because a software search engine should put the owned option next to the one with the biggest brand, and be honest when the owned option shrinks. Our Calendly alternatives page lists everything we track, the scheduling shelf goes wider, or describe it the way you would to a friend: a booking page I can host myself without paying per seat. Before the next seat lands on your invoice, it is worth thirty seconds on the question this series keeps circling. Do you want to rent the calendar, or own it?
