Scheduling infrastructure for absolutely everyone
Cal.com is an open-source scheduling platform that allows users to create booking pages, connect calendars, and automate meeting scheduling. Founded by Peer Richelsen and Bailey Pumfleet, it raised $32.4M and positions itself as a Calendly alternative with a generous free tier. Trustpilot: 4.7/5 from 278 reviews (88% 5-star). GitHub: 964 open issues.
Patterns extracted from real user feedback — not raw reviews.
Trustpilot 1-star review: 'you wait 3 days for a response, only to get template replies' and feels abandoned for complex issues beyond basic video calls. Company responds to 100% of negative reviews within one week, but resolution quality varies. Support not available weekends.
Trustpilot 2-star review (Ben): 'invoices were issued to wrong names despite correct company details. Invoices cannot be reissued' and lacks invoice history in-app. Stated: 'the invoicing and billing side makes it unusable for a serious business.' Problematic for EU VAT compliance.
GitHub issues document: CLIENT_FETCH_ERROR loop with ALLOWED_HOSTNAMES mismatch, V2-API server fails with 'Workspace @calcom/api-v2 not found', translations don't load, GOOGLE_API_CREDENTIALS parsing fails. Hacker News: 'tricky to install for non-technical users.' CALCOM_LICENSE_KEY required for API v2.
GitHub Issue #23104: 'Local dev crazy slow' - page load 10-12 seconds on high-end machines, goal to reduce by 80%. Trustpilot 1-star: 'everything is laggy'. Self-hosted instances particularly affected during traffic spikes. Cold starts historically up to 30 seconds.
Cal.com cannot connect to MS Exchange 2019 calendars, which renders the service completely unusable for organizations using current versions of Microsoft Exchange. This is a dealbreaker for many enterprise users.
The Microsoft Teams integration shows as connected but core functionality (Teams meeting links) is missing. Emails contain only 'MS Teams' text without actual join links. There's a persistent error banner about reconnecting the calendar with necessary permissions due to changes on Microsoft's end.
Initial setup feels complex for new users with advanced features lacking clear guidance. Users report clicking around to find where settings are located. Step-by-step walkthroughs or tooltips are especially needed for team scheduling, permissions, and advanced booking rules.
Even when meetings are set in advance, reminder settings don't work properly. Users report that either party won't join because there are no reminders sent, leading to missed meetings and lost business opportunities.
Users report occasional Cal Video hiccups where starting a meeting shows an error with the video. This requires closing all browser tabs before it connects to the camera, causing awkward delays at the start of important meetings.
The mobile experience could be improved - interface feels small or slightly slow on phones. Settings and advanced options are easier to manage on desktop. A more optimized mobile layout is needed for quick updates on the go.
Generous free plan with unlimited bookings
The free plan includes unlimited bookings, calendar connections, event types, workflows, routing forms, monetization, and webhooks - features that competitors reserve for paid tiers.
Open-source with self-hosting option
Cal.com is fully open-source, allowing developers to self-host the application, customize it, and avoid vendor lock-in. This provides complete control over data and branding.
Deep calendar sync and integrations
Seamless calendar sync with Google, Outlook, and Apple calendars. Prevents double-bookings effectively and offers a professional booking experience with deep customization options.
Lower pricing than Calendly for teams
Cal.com Teams at $15/month per user offers more features at a lower price than Calendly Teams at $20/month per user, with same-day support included.
Eliminates scheduling back-and-forth
The core scheduling functionality works well - it eliminates the back-and-forth of finding meeting times, prevents double-bookings, and saves time and stress for both parties.
Users: 1 user
Limitations: Single user only, Cal.com branding cannot be removed, No round-robin or team scheduling
Users: Per user/month
Limitations: No SSO, No SCIM provisioning, No SOC 2/HIPAA compliance
Users: Per user/month
Limitations: No custom SLAs, No dedicated account manager
Users: For developers building scheduling apps
Limitations: Developer-focused, requires technical implementation, Not for end-user scheduling
Users: Custom
Limitations: Must contact sales for pricing, No self-service signup
Freelancers and solo professionals
The free plan is genuinely generous with unlimited bookings, calendar connections, and event types. A great Calendly alternative if you don't need team features.
Small teams wanting lower costs than Calendly
At $15/user/month vs Calendly's $20/user/month, Cal.com offers significant savings for teams. Features are comparable and include same-day support.
Engineering teams
Open-source, self-hostable, and API-first. Dev teams love Cal.com for customization and integration possibilities.
Privacy-conscious users
Open-source and self-hostable. Users can run Cal.com on their own infrastructure with full data control.
Developers building scheduling into products
The Platform API and open-source nature make it attractive for embedding, but requires commercial license for API v2. Evaluate whether the $299/month Platform plan fits your budget.
Enterprise organizations
Growing enterprise features but less mature than Calendly. Large orgs should evaluate carefully - Cal.com is newer.
Organizations using Microsoft Exchange 2019
Cal.com cannot connect to MS Exchange 2019 calendars, making it completely unusable for organizations on current Exchange versions. Consider Calendly or Microsoft Bookings instead.
EU businesses requiring proper VAT invoicing
The billing system has documented issues with incorrect invoicing, no invoice history in-app, and inability to reissue invoices - problematic for EU VAT compliance requirements.
Non-technical users wanting to self-host
Self-hosting Cal.com requires significant technical expertise, Docker knowledge, and dealing with complex environment variables. The 'free open-source' version is limited without commercial license.
Teams relying heavily on Microsoft Teams video
The Microsoft Teams integration frequently breaks, with meeting links missing from emails. Consider alternatives with more stable MS Teams integration.
Common buyer's remorse scenarios reported by users.
Users attracted by the open-source self-hosting option discover that API v2 and many enterprise features require a commercial license. The free version requires heavy modifications to run independently.
Teams migrated from Calendly to save money, only to find Microsoft Teams integration frequently breaks, with meeting links missing from confirmation emails. Rolling back after team adoption is painful.
Users set up reminder workflows expecting them to work like Calendly, but reminders don't send reliably. This leads to missed meetings with clients and lost business opportunities.
EU businesses discover too late that Cal.com's billing system generates incorrect invoices that can't be reissued. This creates VAT compliance problems and accounting headaches.
Scenarios where this product tends to fail users.
Cal.com cannot connect to on-premise Exchange 2019 calendars at all. The product becomes completely unusable and the organization must find an alternative immediately.
The Microsoft Teams integration breaks frequently due to authentication token changes on Microsoft's end. Emails go out with 'MS Teams' text but no actual meeting links, causing chaos.
Moving from Teams ($15/user) to Organization ($37/user) is a 147% price increase. Add compliance requirements (SOC 2, HIPAA) and the cost advantage over Calendly disappears.
Cold start times can balloon to 30 seconds during traffic spikes. Without proper Redis configuration and optimization, the booking experience degrades significantly.
Cal.com support doesn't operate on weekends. If booking issues arise during a weekend event or conference, you're on your own until Monday.
Calendly
Users needing mature features switch to Calendly. Gain: more integrations, enterprise features, larger support team. Trade-off: closed source, more expensive.
YouCanBook.me
Users needing more reliable integrations and mature feature set switch to YouCanBook.me. Better track record with enterprise calendar systems.
Microsoft Bookings
Organizations already in the Microsoft ecosystem switch to Microsoft Bookings for native Exchange/Teams integration without the compatibility issues.
SavvyCal
Users wanting better UX switch to SavvyCal. Gain: polished interface, overlay calendar. Trade-off: proprietary, smaller.
TidyCal
Budget users switch for one-time payment. Gain: lifetime deal, simple. Trade-off: basic features only.
