Cal.com
“The open-source scheduling infrastructure — self-host it, white-label it, or build on its API.”
Cal.com markets itself directly as the open-source Calendly alternative, and by 2026 it has grown well past that pitch into scheduling infrastructure: a managed cloud product, a fully self-hostable open-source core, a developer-facing Platform API with embeddable 'Atoms' for white-labeled booking inside other apps, and AI-powered phone/booking agents under the separate Cal.ai line. The free plan is unusually generous — unlimited calendars, unlimited event types, and 100+ integrations for a single user — with paid tiers reserved for team coordination, privacy/security controls, and white-labeling.
Tech Specifications
Cal.com is the right call when either ownership of your scheduling data or developer control matters more than out-of-the-box polish — self-hosting eliminates per-seat cost entirely, and the Platform API/Atoms let you embed booking directly into your own product under your own brand, which Calendly simply doesn't offer. For a straightforward team just wanting round-robin and routing on the managed cloud, it's also cheaper than Calendly at the equivalent tier. Where it loses is UI polish and native CRM depth beyond Salesforce/HubSpot — teams that want the most frictionless, best-known booking experience for external clients still lean toward Calendly.
Key Features
- Fully open-source core — self-host on your own infrastructure with complete data control
- Unlimited event types and calendar connections on the free plan, for one user
- Round-robin, collective events, and team/sub-team routing (Teams and Organizations)
- Routing forms to qualify and direct bookings based on invitee answers
- 100+ app integrations, plus two-way Salesforce and HubSpot sync
- One-click Calendly import for switching over existing bookings and event types
- Cal.com Platform API and embeddable 'Atoms' for building scheduling into your own product
- Stripe and PayPal payment collection at booking
- SAML SSO, SCIM provisioning, and HIPAA/SOC 2/ISO 27001 compliance options (Organizations/Enterprise)
- Cal.ai AI phone and booking agents, billed separately from core plans