An open source booking system you host yourself only fits if it books the right thing. Few take client appointments; others book rooms, sell event tickets, take hotel stays or run meeting polls. Decide what you're booking, then read the licence, because some limit commercial or service use.
What are you booking? It sounds like a daft question, but it's the one that sorts this list. Open source booking software covers client appointments, meeting rooms, conference tickets, hotel rooms and group polls, and a tool built for one is no good for another.
So the table comes first: what each tool books, and its licence. The eight are listed in no particular order.
What each tool books, and under which licence
| Tool | Books and licence | Good for |
|---|---|---|
| Alf.io | Event tickets, GPL-3.0 | Ticket sales through to check-in |
| Cal.com (Cal.diy community edition) | Appointment links, MIT (Cal.diy) | Personal booking links on your own server |
| Easy!Appointments | Client appointments, GPL-3.0 | Booking services and providers on your own server |
| LibreBooking | Rooms and equipment, GPLv3 | Shared rooms and equipment |
| Nextcloud Calendar (Appointments) | Appointments inside a suite, AGPL-3.0 | Teams already running a self-hosted suite |
| pretix | Event tickets, AGPL-3.0 with extra terms | Ticket shops for events and conferences |
| QloApps | Hotel stays, OSL-3.0 | Small hotels taking direct bookings |
| Rallly | Meeting polls, AGPL-3.0 | Finding a time that suits a group |
Only three of these take client appointments
If you want clients to pick a slot with you or your staff, only about three of the eight do that job. Two are appointment tools, and the third adds bookable slots to a collaboration suite you'd have to run in full. The rest book something else: rooms and equipment, event tickets, hotel stays or a shared meeting time. They're here because people searching for open source booking need them, not because they'll run your diary.
The bigger surprise is the best-known name. Cal.com's own README says the self-hostable open source version is a stripped-down fork called Cal.diy, with all enterprise code removed, and that it's "strictly recommended for personal, non-production use". Commercial users are pointed to hosted Cal.com or an on-premises enterprise deal. And one ticketing platform's licence adds a term the plain AGPL doesn't have: pretix may not be offered to third parties as a service, so an agency can't resell it as hosted ticketing for clients.
Grouped by what's being booked
Appointments and meeting times
Easy!Appointments is the most direct fit for a business taking appointments on its own server, and its makers also sell managed hosting. Rallly doesn't take bookings at all; it finds a time a group can meet.
Rooms and equipment
LibreBooking reserves shared resources rather than people's time. Nextcloud users get appointment slots in the Calendar app, but you need a whole suite install, not a standalone booking tool.
Events and stays
Alf.io and the ticket shop above sell event places. QloApps is a hotel booking engine. None of them is appointment software, so don't plan a client diary around them.
The eight tools, in no particular order
Alf.io
Best for: Event organisers selling tickets and checking people in on the day, with a Docker image and a privacy-minded pitch, as the vendor puts it.
Cal.com (Cal.diy community edition)
Best for: Personal booking links on your own server. The README says the self-hosted fork has enterprise code removed and is for personal, non-production use.
Easy!Appointments
Best for: Small businesses taking client appointments on their own server, with services, providers, customer records and calendar sync, plus optional managed hosting.
LibreBooking
Best for: Offices, labs and schools reserving rooms and equipment, with Docker support. Its README says run 7.2.0 or later, as older versions aren't patched.
Nextcloud Calendar (Appointments)
Best for: Teams already on a self-hosted collaboration suite who want bookable appointment slots in its Calendar app, with a video room added if needed.
pretix
Best for: Conferences, venues and event teams running their own ticket shop and booking backend, with add-on products from the company behind it.
QloApps
Best for: Independent hotels up to chains wanting a booking engine and property management in one system, with hosting and add-ons sold separately.
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Rallly
Best for: Groups picking a meeting time: propose slots, share a link and let everyone vote, which the site says includes finalising polls for free.
Advice on matching the tool to the booking
Write down one sentence describing a booking: who books, what they book and what happens next. If it's a client booking time with a person, look at the appointment tools first and check the licence limits on the best-known one before you build a business on it. If it's a room, a ticket or a hotel night, go straight to the tool built for that, because bending an appointment tool to sell tickets wastes weeks.
Whichever you pick, self-hosting means you look after updates and security, which is why one project's README warns everyone on old versions to upgrade. For hosted options, our guides to online scheduling software and booking software for small businesses cover tools that run everything for you.
If you run a salon or a clinic
A salon, clinic or studio usually needs reminders, staff rotas, deposits and a booking page that just works on a busy Saturday. Few self-hosted tools here are built for that, and running one means you're also the IT department. For most of these businesses a hosted booking tool is the safer route, and self-hosting makes sense only if you have technical help and a strong reason to keep the data on your own server.
Do you make open source booking or scheduling software? Tool makers can ask to be considered for a featured place on this list.
Want your tool on this list? Featured spots and reviews here are paid partnerships. Here's how to partner with me.
Frequently asked questions
Is there an open source alternative for client appointment booking?
Yes, a few. Self-hosted appointment tools let clients choose a service, provider and time on your own server. Check the licence and the project's own guidance on business use.
Can I use the self-hosted Cal.diy edition for my business?
Its README says the community edition is strictly recommended for personal, non-production use and points commercial users to the hosted product or an enterprise deal.
What's the difference between appointment booking and resource booking?
Appointment booking reserves a person's time, such as a consultation. Resource booking reserves a thing, such as a meeting room, desk or piece of equipment.
Can I resell an open source ticketing system to clients?
It depends on the licence. One ticket platform here adds a term barring you from offering it to third parties as a service, so read the licence file before you sell hosting.
Do I need a server to run open source booking software?
Yes. You'll need hosting, a database for most tools, and someone to apply updates and security fixes.
Is a meeting poll tool the same as scheduling software?
Not quite. A poll finds a time a group can meet. Scheduling software takes bookings into open slots on your calendar.
