Appointment Scheduling Software · 2026 reliability ranking

Most Reliable Appointment Scheduling Software (2026)

Q: What is the most reliable scheduling app?

Based on the last 90 days of data, Calendly is the most reliable scheduling app we track, with a reliability score of 100.0/100 and 100% uptime.

Q: How do you measure scheduling app reliability?

We poll each vendor's public status page every few minutes, record every incident, and run our own uptime checks against each vendor's login and customer-facing pages. Uptime (40%), incident frequency (20%), average time to resolve (20%) and transparency (20%) combine into one score out of 100.

Q: How often are these rankings updated?

Continuously. Status pages and uptime checks run every five minutes and scores are recalculated several times an hour.

Q: Can vendors pay to rank higher?

No. Sponsored placements are clearly labelled, shown separately from the rankings and never change a vendor's score.

We ranked 13 scheduling apps by real-world reliability over the last 90 days, using 23 status page incidents and our own around-the-clock uptime checks. Scheduling apps run the booking page clients use to pick a time, the calendar sync that blocks double bookings, and the reminder emails and texts that keep people from forgetting. When one fails, clients can't book, slots get double-booked because a calendar stopped syncing, or no-shows rise because reminders never went out. For a business that fills its day through online bookings, a few hours of downtime means missed appointments and lost revenue that are hard to recover.

Last updated Nov 1, 2026 · How we score

Most reliable scheduling app: Calendly (score 100.0/100). Highest uptime: Calendly (100%). Fewest incidents: Calendly (0 in 90 days). Fastest to resolve: Square Appointments (avg 12h 49m).

#	Vendor	Score	Uptime (90d)	Incidents	Avg resolve	Transparency	Status now
1	CalendlyCalendly is an online appointment scheduling application headquartered in Atlanta, Georgia.	100.0	100%	0	—	100/100	Operational
2	DoodleDoodle is an online scheduling and meeting poll service based in Zurich, Switzerland.	100.0	100%	0	—	100/100	Operational
3	SavvyCalSavvyCal is an online scheduling application for sharing availability and booking links.	100.0	100%	0	—	100/100	Operational
4	Sign In Scheduling (formerly 10to8)Sign In Scheduling, formerly 10to8, is an appointment scheduling application from UK-based Sign In App.	100.0	100%	0	—	100/100	Operational
5	YouCanBookMeYouCanBookMe is an online scheduling application based in the United Kingdom.	100.0	100%	0	—	100/100	Operational
6	Cal.comCal.com is an open-source scheduling application offered as a hosted service and as self-hosted software.	86.2	100%	3 (2 major)	—	100/100	Operational
7	Chili PiperChili Piper is a meeting scheduling and inbound lead routing application for sales teams.	60.6	99.44%	1 (1 major)	23h 53m	100/100	Operational
8	Square AppointmentsSquare Appointments is the appointment booking and point-of-sale software from Block, Inc.'s Square for salons, spas and other service businesses.	53.3	98.93%	12	12h 49m	100/100	Operational
9	Acuity SchedulingAcuity Scheduling is an online appointment scheduling application owned by Squarespace.	45.5	98.16%	7 (3 major)	15h 44m	100/100	Operational

Appointment Scheduling Software reliability at a glance

Across the 9 ranked scheduling apps, average 90-day uptime is 99.61%. Reliability scores range from 100.0 (Calendly) to 45.5 (Acuity Scheduling).
Together they published 23 incidents in the last 90 days, 6 of them partial or major outages.
Calendly, Doodle, SavvyCal, Sign In Scheduling (formerly 10to8), YouCanBookMe reported no incidents at all in that time.
The typical vendor takes 15h 44m to resolve an incident. Square Appointments is fastest, at 12h 49m on average.
Square Appointments reported the most incidents (12 in 90 days).

What to check before you choose a scheduling app

Check how often the public booking page and calendar sync fail. Those two stop new bookings or cause double bookings; an admin dashboard outage is easier to live with.
Look for reminder and notification incidents in the history. Delayed or missing reminders show up later as no-shows.
Check whether the vendor reports problems with the calendars it depends on (Google, Microsoft 365, iCloud), since those outages reach your bookings too.
Subscribe to the vendor's status page so you hear about a booking outage before clients start calling.