Cost to Build a Scheduling App Like Calendly in 2026

What a Calendly-style scheduling app includes

Calendly says more than 50 million people use it across 240 countries, and that it has booked over 1.3 billion meetings with 100+ integrations. The idea is simple: share a link, the other person picks a free time, and the meeting lands in both calendars. Doing that reliably means reading busy times from several calendars, handling time zones and recurring events, and never offering a slot that has just been taken.

• Host app: sign-up, calendar connections, event types with durations and buffers, working hours, date overrides, booking limits.
• Booking page: public link, time zone detection, available slots, invitee questions, confirmation, reschedule and cancel links.
• Notifications: calendar invites, email confirmations and reminders, and later SMS and webhooks.
• Business layer: plans and billing, team accounts, admin console, analytics.

How much does it cost to build an app like Calendly?

Feature-by-feature cost breakdown (MVP)

Hours include design, development and testing for each component. Costs apply our blended rate of $28 to $38 an hour, and the headline range allows plus or minus 15 percent on hours. Open this setup in the calculator to change it. The three integrations are Google Calendar, Microsoft 365 calendars and one video-meeting provider. The GDPR line covers consent, data export and deletion.

Why the availability engine is the hard part

Most of the risk in a scheduling app sits in one function: given a host, an event type and a date range, which start times are free? The answer combines working hours in the host's time zone, date overrides, buffers before and after meetings, minimum notice, daily limits, and busy times from every connected calendar. Daylight saving changes move slots by an hour twice a year, and recurring events in a calendar expand into many busy blocks.

Two rules keep it reliable. First, cache busy times but refresh them when the calendar provider sends a change notification, so the page is fast and still current. Second, check again at the moment of booking and let the database reject a second booking for the same slot. Write automated tests for time zones, overrides and overlapping calendars before building screens; they catch the bugs users notice first.

MVP vs full product: what gets added

Team and timeline

The MVP suits 2 senior full-stack engineers, a designer (part-time), QA and a delivery lead. The build takes 9 to 17 weeks. Start the Google OAuth verification as soon as the consent screen and privacy policy exist, because it runs alongside the build. Build the availability engine and its tests first, since every other feature depends on it, then booking pages, notifications and billing.

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Running costs to plan for

• Email delivery for confirmations and reminders, and SMS if you offer it.
• Hosting, background workers and monitoring for calendar sync.
• Payment processing on subscriptions.
• A security assessment if you ever add restricted Google scopes such as Gmail.
• A maintenance retainer of $1.5k to $8k per month, since calendar APIs and video provider APIs change.

How Calendly makes money

Calendly sells seats. Its pricing page lists a free plan with one event type and one calendar connection, Standard at $10 per seat a month and Teams at $16 per seat a month, both billed yearly, and Enterprise from $15,000 a year starting at 50 seats. Seats are for hosts; people booking a meeting do not need one. The free plan spreads the product, because every invitee sees a booking page, and team features such as round-robin, routing and Salesforce sync drive upgrades.

A new scheduling product rarely wins as a general tool. It wins in a niche where booking carries more context: clinics, tutors, salons, sales teams with complex routing or recruiters. Price per seat or per location, and keep the free tier narrow.

Calendar permissions, Google verification and GDPR

• Ask for the narrowest scopes. Google lists separate Calendar scopes for free/busy only, events only and full calendar access, and tells developers to request the most narrowly focused scope possible. For Microsoft, Graph offers Calendars.ReadBasic, Calendars.Read and Calendars.ReadWrite.
• Plan for sensitive-scope verification. Google gives reading events stored in Google Calendar as an example of a sensitive scope. Public apps using sensitive scopes must pass verification, which Google says can take up to 10 days, with a justification and a demo video for each scope.
• Avoid restricted scopes unless you need them. Restricted scopes, such as some Gmail access, require an annual security assessment by a Google-approved third party, and Google warns verification can take several weeks. A scheduling app does not need them.
• GDPR applies to non-EU companies too when they offer services to people in the EU. Your business customers will ask for a data processing agreement, because Article 28 requires a contract with any processor, and users can ask for their data to be erased under Article 17.

How to reduce the cost

1. Launch on the web only; booking pages and settings work well in a mobile browser.
2. Support Google and Microsoft calendars first; they cover most business users.
3. Use one video provider at launch and add others on request.
4. Request free/busy and event scopes only, so verification stays in the sensitive tier.
5. Pick a niche and build the one feature general tools do badly for it.

We built the CareFlair marketplace with an availability calendar and recurring bookings, and TamTracker, a multi-tenant SaaS with Google sign-in, nine OAuth and API integrations, Stripe subscriptions and scheduled digests. See SaaS development, our SaaS development cost guide and multi-tenant SaaS architecture.

Sources

• Innovation Insight app development cost calculator and pricing
• Calendly, About us: https://calendly.com/about
• Calendly pricing: https://calendly.com/pricing
• Google, Calendar API scopes: https://developers.google.com/workspace/calendar/api/auth
• Google, sensitive scope verification: https://developers.google.com/identity/protocols/oauth2/production-readiness/sensitive-scope-verification
• Google, restricted scope verification: https://developers.google.com/identity/protocols/oauth2/production-readiness/restricted-scope-verification
• Google Calendar push notifications: https://developers.google.com/workspace/calendar/api/guides/push
• Microsoft Graph, calendar getSchedule: https://learn.microsoft.com/en-us/graph/api/calendar-getschedule
• Regulation (EU) 2016/679 (GDPR): https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32016R0679
• RFC 5545, iCalendar: https://www.rfc-editor.org/rfc/rfc5545