OnSched

OnSched is a white-label scheduling API that positions itself as mission-critical booking infrastructure for enterprise and startup developers with complex requirements. Rather than a booking page, it provides the scheduling engine — availability, appointments, resources, and calendar coordination — behind a single API key, and reports over 22 million appointments scheduled through it.

The feature set is developer-oriented: calendar sync, SMS notifications and email templates, OAuth 2.0, custom fields and permissions, account levels for multi-tenant setups, world timezone handling, a dashboard, webhooks, and Zapier integration. It is built for teams embedding scheduling across industries such as healthcare, finance, insurance, logistics, e-commerce, and recruitment, and is HIPAA and SOC 2 compliant for regulated use.

Pricing is usage-based and enterprise-tier rather than consumer: Starter at $299/month (up to 300 appointments), Growth at $699 (up to 3,000), and Scale at $1,799 (3,000+), with a developer sandbox for building against the API. OnSched fits companies that need dependable scheduling as embedded infrastructure inside their own software — not individuals or small teams after a personal booking link.