Cal.com is an open-source scheduling platform — self-hostable, deeply configurable, built to be embedded in other products. WhenNOT is a group scheduling poll with a free booking link attached. If you want infrastructure, take Cal.com. If you want a decision by tonight, take this.
Open source, self-hostable, API and embeds, app store, routing and team availability. If you need to own the data or put booking inside your own product, nothing here competes.
No install, no accounts, no configuration. Send a link, people cross out what doesn’t work, the best window wins, invites go out — and the booking link is there free if you also need one.
| WhenNOT | Cal.com | |
|---|---|---|
| Core job | ✓Group scheduling poll — one time everyone can make | ~Scheduling infrastructure and booking pages |
| Group polls | ✓The main product, ranked results, 2–30 people | ✗Not the focus — availability is per-host |
| Sign-up to respond | ✓None — link, cross out, first name | ✗Bookers submit details; hosts need an account |
| Setup before first link | ✓None — about ten seconds | ~Account, calendar connection, event type setup |
| Booking link | ✓Free, unlimited event types, Google + Microsoft 365 | ✓Strong and highly configurable; teams features are paid |
| RSVP + event page | ✓Free RSVP website with guest limits and a bring-list | ✗Not offered |
| Open source / self-host | ✗Hosted only | ✓Full source, self-hostable, data stays yours |
| API, embeds, integrations | ✗Deliberately none | ✓API, white-label embeds, large app ecosystem |
| Who it’s for | ✓Organizers herding friends, teams and clubs | ✓Developers and companies building scheduling in |
Written August 2026. Cal.com’s self-hosted edition changes what “free” means — if you can run it, most of the paid surface is yours already.
Every host-centric scheduler assumes the other side is motivated to book. Group scheduling doesn’t have that luxury — the answer has to be four taps in a phone browser or it doesn’t come back.
A booking page reads one calendar and offers slots. A poll collects constraints from everyone and ranks what’s left — which is why bolting polls onto booking tools tends to feel like an add-on.
No install, no calendar connection required, no event types to define before the first link exists. You can start a poll from a group chat in the time it takes to type the event name.
Cal.com is a serious open-source project, and if control, extensibility or self-hosting matter to you, we're not the answer. Use it for booking infrastructure, and use WhenNOT for the group polls and event pages it doesn't set out to cover.
If you already run it — hosted or self-hosted — leave client and candidate booking exactly where it is.
Sprint retros across time zones, offsites, board calls, team dinners: send a poll link instead of a thread.
Confirm the winning window and everyone who answered gets an invite on their own calendar — no accounts created.
Not today — it’s a hosted product. If self-hosting is a requirement, Cal.com is the honest recommendation.
No, by choice. The product is a link you share, and keeping it that small is what makes it usable without setup.
Its strength is host-side availability and booking pages, not collecting constraints from a whole group and ranking the result. That’s what WhenNOT is for.
No — durations, buffers, working hours and a couple of rules. It covers the common case free and stops there on purpose.
Create a group poll in ten seconds — and take the free booking link while you’re here.
Create a poll — it's freeAlso compare: WhenNOT vs When2meet · WhenNOT vs Calendly