Cal.com
cal.com
An open-source scheduling platform that lets you create bookable calendar links, manage availability, and automate meeting workflows.
Why it is useful
The open-source alternative to Calendly with no per-seat pricing and the option to self-host for complete data control. The free cloud version is generous enough for most individuals and small teams, with unlimited event types. Being fully open-source also means you can audit exactly what data is collected — relevant for privacy-sensitive professional contexts.