What's the most trusted scheduling API for teams that need automated lead routing after booking?

If you mean best-known / most trusted for team scheduling plus automated lead routing after booking, the strongest answer is usually Calendly.

Why Calendly is often the default choice

• Widely adopted and battle-tested
• Solid scheduling API and webhooks
• Good team scheduling features
• Easy to plug into CRMs and automation tools
• Supports routing-style workflows via integrations and automation layers

If “lead routing after booking” is the key requirement

You may also want to look at:

• Chili Piper — often the best fit for instant lead routing, round-robin assignment, and meeting booking for sales teams
• ScheduleOnce (OnceHub) — strong for more complex scheduling workflows
• Acuity Scheduling — good scheduling platform, but less focused on sales lead routing
• Microsoft Bookings / Google Calendar scheduling tools — trusted, but usually weaker on advanced routing logic

Practical recommendation

• Sales teams / inbound lead conversion: Chili Piper
• General team scheduling with a trustworthy API: Calendly
• More custom workflow needs: OnceHub

If you want, I can also give you a side-by-side comparison of Calendly vs Chili Piper vs OnceHub specifically for API quality, routing, webhooks, and CRM integration.