Best Open-Source Scheduling Software 2026: 6 Options Compared
Best open-source Scheduling Software compared: Cal.com, Easy!Appointments, Rallly, LibreBooking and 2 more, with licenses, platforms and prices from official pages checked October 24, 2026.
•3 min read•Email, Calendar & Scheduling
Quick comparison
| Tool | Price | Platforms | Best for | Tested |
|---|---|---|---|---|
| Cal.com | Free (Free plan for 1 user; the page says scheduling has no usage limits); paid from $12 per user/month (Teams, yearly billing; dollar sign only) | Web, Self-hosted | Solo professionals replacing Calendly | Docs only |
| Easy!Appointments | Free (Free for personal and commercial use; you host it) | Self-hosted (PHP, MySQL) | Service businesses | Docs only |
| Rallly | Free (Free: create, share and vote on polls with no participant limit and no account needed; inactive polls are deleted automatically); paid from $4.67 per seat/month, billed yearly (Pro) | Web, Self-hosted | Finding a time for a group | Docs only |
| LibreBooking | Free (Free and open source) | Web, Self-hosted | Booking rooms and equipment | Docs only |
| Thunderbird Appointment | Free (Source code is free and open source; a hosted service also exists at appointment.tb.pro) | Web, Self-hosted (Docker) | Thunderbird users | Docs only |
| Nextcloud | Free (Community server is free to self-host and the Nextcloud-branded desktop and mobile apps are free); paid from EUR 71.29 per user/year (Enterprise Standard at 100 users, 100-user minimum) | Web, Self-hosted, Desktop app, Mobile app | Existing Nextcloud servers | Docs only |
Independent comparison. Paid placements are labelled separately; editorial links earn no affiliate commissions. Learn more.
See the tools in action
Images from the linked documentation. Versions and features may differ from current plans.
Good fit if
- You want a Calendly replacement for yourself (Cal.com is the pick)
- You run a clinic or salon with several staff (Easy!Appointments is the pick)
- You are polling friends for a dinner date (Rallly is the pick)
- You manage a pool of meeting rooms (LibreBooking is the pick)
Not ideal if
- You cannot host, patch and back up a server yourself and want a vendor to run it
Scheduling software covers two jobs. Booking pages let clients pick a slot from your availability, and Cal.com, Easy!Appointments, Thunderbird Appointment and Nextcloud's Calendar appointments cover that. Group polls help a bunch of people find a time that works for everyone, which is Rallly's specialty. LibreBooking is different again: it books resources such as meeting rooms and equipment rather than people. Cal.com is the most complete booking tool and its repository is MIT licensed, though check which edition you deploy. Easy!Appointments suits service businesses with several providers and runs on PHP and MySQL. Thunderbird Appointment is newer and tied to the Thunderbird ecosystem. If you already host Nextcloud, its calendar appointments cost nothing extra. Self-hosting saves the monthly fee of a Calendly-style tool, but you also take on email delivery, which is the usual weak point: reminders that land in spam defeat the purpose. Connecting calendars such as Google or Outlook requires API credentials you set up yourself. Pick a hosted free plan first if you only need one booking link. The licences and plans below come from each project's own pages as of the check date.
Cal.com
MIT repository licence and a free hosted plan for one user. The most complete booking tool here, with scheduling listed as having no usage limits.
Price: Free (Free plan for 1 user; the page says scheduling has no usage limits); paid from $12 per user/month (Teams, yearly billing; dollar sign only) (Cal.com pricing, checked 2026-10-23).
Platforms and license: Web, Self-hosted. MIT (repository LICENSE) (open source) (license source).
Project activity: 49.4k GitHub stars · latest release v6.2.0 (Mar 1, 2026) · last commit Oct 27, 2026
Best for: Solo professionals replacing Calendly.
Easy!Appointments
GPL-3.0, free for personal and commercial use, and you host it. Handles several providers and services.
Price: Free (Free for personal and commercial use; you host it) (Easy!Appointments pricing, checked 2026-10-23).
Platforms and license: Self-hosted (PHP, MySQL). GPL-3.0 (open source) (license source).
Project activity: 4.5k GitHub stars · latest release 1.6.1 (Oct 19, 2026) · last commit Oct 26, 2026
Best for: Service businesses.
Rallly
AGPL-3.0 poll tool: create, share and vote on polls with no participant limit and no account needed for voters; inactive polls are deleted automatically.
Price: Free (Free: create, share and vote on polls with no participant limit and no account needed; inactive polls are deleted automatically); paid from $4.67 per seat/month, billed yearly (Pro) (Rallly pricing, checked 2026-10-23).
Platforms and license: Web, Self-hosted. AGPL-3.0 (open source) (license source).
Project activity: 5.3k GitHub stars · latest release v4.16.3 (Oct 26, 2026) · last commit Oct 26, 2026
Best for: Finding a time for a group.
LibreBooking
GPL-3.0 resource scheduling solution for rooms, equipment and similar assets. Not meant for client appointments.
Price: Free (Free and open source) (LibreBooking pricing, checked 2026-10-24).
Platforms and license: Web, Self-hosted. GPL-3.0 (open source) (license source).
Project activity: 839 GitHub stars · latest release v7.1.0 (Oct 13, 2026) · last commit Oct 25, 2026
Best for: Booking rooms and equipment.
Worth knowing: GitHub describes it as an open-source resource scheduling solution. License taken from the repository metadata and LICENSE file; description from the project README. No paid plan was checked.
Thunderbird Appointment
MPL-2.0 booking tool from the Thunderbird team, Docker-based, with a hosted service whose pricing was not checked.
Price: Free (Source code is free and open source; a hosted service also exists at appointment.tb.pro) (Thunderbird Appointment pricing, checked 2026-10-24).
Platforms and license: Web, Self-hosted (Docker). MPL-2.0 (open source) (license source).
Project activity: 556 GitHub stars · latest release r-0948 (Oct 16, 2026) · last commit Oct 27, 2026
Best for: Thunderbird users.
Nextcloud
AGPL-3.0 suite whose Calendar app lets you create appointment configurations that others can book. Free if you already host Nextcloud.
Price: Free (Community server is free to self-host and the Nextcloud-branded desktop and mobile apps are free); paid from EUR 71.29 per user/year (Enterprise Standard at 100 users, 100-user minimum) (Nextcloud pricing, checked 2026-10-22).
Platforms and license: Web, Self-hosted, Desktop app, Mobile app. AGPL-3.0 (open source) (license source).
Project activity: 37.3k GitHub stars · latest release v33.0.10 (Oct 15, 2026) · last commit Oct 27, 2026
Best for: Existing Nextcloud servers.
Which one to pick
- You want a Calendly replacement for yourself: Cal.com
- You run a clinic or salon with several staff: Easy!Appointments
- You are polling friends for a dinner date: Rallly
- You manage a pool of meeting rooms: LibreBooking
Limits of this review
Docs-only for Cal.com, Easy!Appointments, Rallly, LibreBooking, Thunderbird Appointment, Nextcloud: we did not install or run them, so feature claims come from vendor pages. Vendor prices and free limits change; confirm on the linked pricing page before you commit.
Related guides
More in Email, Calendar & Scheduling
All Email, Calendar & Scheduling alternatives →Sources
Kevin Fan
Kevin Fan is a SaaS founder. He runs Free Instead Of, which tracks free and open-source alternatives to paid software and checks each price and free-plan limit against the vendor's own pages.
Methodology
Based on official pricing, license and product pages checked between 2026-10-22 and 2026-10-24: Cal.com, Easy!Appointments, Rallly, LibreBooking, Thunderbird Appointment, Nextcloud. Prices, free limits and licenses are the figures shown on those pages on those dates. No tool on this page was installed or run. No accounts were created.