Best Open Source Scheduling Tools in 2026

TL;DR

Calendly Teams costs $16/user/month — a 10-person sales team pays $1,920/year for booking links. Cal.com is the most complete open source replacement with routing forms, round-robin scheduling, and payment collection. Rallly is the perfect Doodle replacement for group availability polls. Easy!Appointments handles service-based booking for clinics, salons, and consultants.

Key Takeaways

Cal.com (AGPL-3.0, 33K+ stars) is the most feature-complete Calendly replacement with managed event types, team scheduling, and workflow automations
Rallly (AGPL-3.0, 3.5K+ stars) is a focused group scheduling poll tool — share a link, participants vote on time slots, no accounts required
Easy!Appointments (GPL-3.0, 3K+ stars) handles multi-provider service booking for healthcare, beauty, and professional services
Schej (MIT, 1K+ stars) is the When2meet replacement for quick group availability checks
Self-hosting Cal.com on a $6/month VPS saves $906–3,744/year vs Calendly Teams depending on team size
Cal.com is API-first: the entire product is scriptable, embeddable, and extensible

Why Scheduling Software Costs Are Surprisingly High

Scheduling seems like a simple problem — share availability, pick a time. But the feature requirements for business scheduling add up quickly. Calendly's per-seat pricing reflects the reality that individual contributors, account executives, support agents, and customer success managers all need booking links. At $16/user/month, a 20-person customer-facing team pays $3,840/year.

Beyond cost, data residency matters. Scheduling metadata — who met with whom, how often, for how long — is competitive intelligence. A sales team's meeting history with prospects reveals pipeline activity. Storing this on Calendly's servers is a business intelligence leak to a third party.

Self-hosted scheduling tools keep your meeting data on your infrastructure and let you query it directly.

Cal.com — Best Overall Scheduling Platform

Cal.com is the most ambitious open source scheduling project. The codebase is a Next.js monorepo with a sophisticated event management system — routing forms, team-level event types, managed events (where admins control what event types team members can offer), and a full workflow automation engine.

Event types are Cal.com's core primitive. An event type defines the meeting duration, availability windows, buffer times, locations (Zoom, Meet, Teams, physical address), and confirmation settings. You can have unlimited event types per user — one for 15-minute quick calls, another for 60-minute demos, another for 90-minute workshops with different availability rules.

Routing forms are the feature that makes Cal.com genuinely powerful for sales and support teams. Before a prospect books a meeting, they fill out a form. Based on their answers (company size, use case, region), the routing form automatically assigns them to the appropriate team member or calendar. This eliminates manual lead routing.

# Cal.com Docker Compose (simplified)
services:
  calcom:
    image: calcom/cal.com:latest
    environment:
      - DATABASE_URL=postgresql://calcom:password@db:5432/calcom
      - NEXTAUTH_SECRET=your-nextauth-secret
      - NEXTAUTH_URL=https://cal.yourdomain.com
      - CALENDSO_ENCRYPTION_KEY=your-encryption-key
      - EMAIL_SERVER_HOST=smtp.yourprovider.com
      - EMAIL_FROM=noreply@yourdomain.com
    ports:
      - "3000:3000"
    depends_on:
      - db
  db:
    image: postgres:15
    environment:
      POSTGRES_DB: calcom
      POSTGRES_USER: calcom
      POSTGRES_PASSWORD: password
    volumes:
      - calcom_db:/var/lib/postgresql/data
volumes:
  calcom_db:

Calendar integrations cover Google Calendar, Outlook/Microsoft 365, Apple Calendar (via CalDAV), and FastMail. Cal.com checks your connected calendars for conflicts in real-time when displaying available slots to bookers.

Video conferencing auto-creation is built in: when a booking is confirmed, Cal.com automatically creates a Google Meet, Zoom, or Teams meeting and adds the link to both participants' calendars. No manual step required.

Key features:

Unlimited event types per user
Routing forms for meeting assignment
Round-robin and collective team scheduling
Managed event types (admin-controlled)
Workflow automations (reminders, follow-ups via email/SMS)
Embeddable booking widget (inline, popup, or full-page)
Stripe/PayPal payment collection for paid sessions
Multi-timezone support (auto-detects attendee timezone)
Availability override for specific dates
Buffer times and minimum notice windows
REST API and webhooks
SAML/SSO integration

Limitations: Cal.com's self-hosted setup requires 1–2 GB RAM and a PostgreSQL database. The monorepo is complex to self-host — follow the official Docker guide carefully. Email delivery requires an external SMTP service (Resend, Postmark, or SES).

Rallly — Best Group Scheduling (Doodle Replacement)

Rallly solves a specific problem: finding a meeting time that works for a group. You create a poll with candidate dates and times, share the link, and participants vote without creating accounts. The poll shows a heat map of availability.

The experience is noticeably cleaner than Doodle, which has added ads and friction to its free tier. Rallly is ad-free, account-free for participants, and deploys in under 10 minutes.

# Rallly Docker Compose
services:
  rallly:
    image: lukevella/rallly:latest
    environment:
      - DATABASE_URL=postgres://rallly:password@db:5432/rallly
      - NEXTAUTH_SECRET=your-secret
      - NEXTAUTH_URL=https://poll.yourdomain.com
      - SUPPORT_EMAIL=support@yourdomain.com
      - SMTP_HOST=smtp.yourprovider.com
      - SMTP_PORT=587
      - SMTP_USER=noreply@yourdomain.com
      - SMTP_PWD=your-smtp-password
      - SMTP_SECURE=false
    ports:
      - "3000:3000"
  db:
    image: postgres:15
    environment:
      POSTGRES_DB: rallly
      POSTGRES_USER: rallly
      POSTGRES_PASSWORD: password
    volumes:
      - rallly_db:/var/lib/postgresql/data
volumes:
  rallly_db:

Key features:

Create date/time polls with multiple candidate slots
Participants vote without creating accounts
Timezone auto-detection per participant
Final time selection notification to all participants
Video conferencing link attachment
Mobile-friendly interface

Easy!Appointments — Best for Service Businesses

Easy!Appointments is purpose-built for service-based scheduling: the kind of booking where a customer selects a service, chooses a provider (hairdresser, doctor, consultant), and picks an available slot within that provider's working hours.

The service/provider/customer model is more appropriate for clinics, salons, and service businesses than Cal.com's person-centric model. A hair salon can set up "Haircut," "Color," and "Blowout" services with different durations, then assign providers who offer each service, and customers book the service+provider combination.

Google Calendar sync keeps provider availability current. Providers add personal appointments to Google Calendar, and Easy!Appointments respects those blocks when displaying booking availability.

The interface is PHP-based with a traditional admin panel — less modern than Cal.com but stable and functional.

Key features:

Services with configurable durations and prices
Multiple providers per service
Working hours and break management per provider
Customer booking page with service/provider selection
Google Calendar sync
Email notifications (booking confirmation, reminders, cancellations)
Multi-language support
REST API

Full Comparison

Feature	Cal.com	Rallly	Easy!Appointments
License	AGPL-3.0	AGPL-3.0	GPL-3.0
Min RAM	1–2 GB	512 MB	256 MB
Use Case	Personal + team booking	Group polls	Service businesses
Multiple Providers	✅ Round-robin	N/A	✅ Native
Group Availability	✅ Collective	✅ Primary feature	❌
Payment Collection	✅ Stripe	❌	✅
Routing Forms	✅	❌	❌
Embeddable Widget	✅	❌	✅
Calendar Sync	✅ Google, Outlook, Apple	❌	✅ Google
Video Auto-Create	✅ Zoom, Meet, Teams	✅	❌
API	✅	Limited	✅

Decision Framework

Choose Cal.com if: You're replacing Calendly for individual or team scheduling. Need routing forms, round-robin, workflow automations, or embedded booking.

Choose Rallly if: You need to find a time that works for a group of people — your team, a committee, external stakeholders. The Doodle poll format for any group meeting.

Choose Easy!Appointments if: You run a service business (clinic, salon, legal, consulting) where customers book specific services with specific providers.

Choose Schej if: You want the simplest possible When2meet-style grid availability check without any server overhead.

Cost Comparison

Team Size	Calendly Teams	Cal.com Self-Hosted	Annual Savings
5 users	$960/year	$72/year (VPS)	$888
20 users	$3,840/year	$96/year	$3,744
50 users	$9,600/year	$144/year	$9,456

Calendly's per-seat cost adds up fast for GTM teams. Cal.com's self-hosted version costs the same for 5 users or 500.

Integrating Scheduling with Your Calendar Stack

Scheduling tools are only useful if they stay in sync with the calendars your team and your invitees actually use. Integration quality is the most practically important dimension for evaluating self-hosted scheduling tools.

Cal.com's calendar integrations cover the major providers: Google Calendar (read availability and write new events), Outlook/Microsoft 365 Calendar, Apple Calendar via CalDAV, and any CalDAV-compatible calendar server. For self-hosted calendar infrastructure (Nextcloud Calendar, Radicale), the CalDAV integration allows Cal.com to check availability against a completely self-hosted calendar stack. The OAuth flows for Google and Microsoft calendars are set up during initial configuration by providing client credentials from Google Cloud Console or Azure AD. Cal.com also supports two-directional sync — booked meetings appear in your Google Calendar and in Cal.com simultaneously, and declining a Google Calendar event can cancel the Cal.com booking.

Video conferencing integration handles the meeting link creation: Cal.com integrates with Zoom, Google Meet, Microsoft Teams, and self-hosted options including Daily.co (limited self-host) and Jitsi Meet (via direct link configuration). For teams committed to a fully self-hosted stack, the Jitsi integration (configuring a base Jitsi room URL per event type) avoids dependency on Zoom or Google Meet.

Rallly's calendar integration is simpler by design — it's a group availability polling tool, not a booking system. Rallly exports selected meeting time as an ICS calendar event that participants can add to any calendar. The integration depth is intentionally minimal: Rallly solves the "agree on a time" problem and hands off to your existing calendar system for the actual scheduling.

For complete scheduling reliability, high-availability deployment matters. See How to Self-Host Rallly 2026 for infrastructure setup, and Rallly vs Cal.com 2026 for a detailed comparison of when each tool is the right choice.

Self-Hosting Requirements for High-Availability Scheduling

Scheduling tools have stricter uptime requirements than many other self-hosted tools. If your documentation wiki is down for an hour, the impact is inconvenience. If your booking page is unavailable during business hours when prospects are trying to book discovery calls, the impact is lost pipeline.

Cal.com's architecture requirements for production deployment are modest but specific. The Next.js application requires Node.js 18+, PostgreSQL 13+, and a Redis instance for queue processing (email delivery, webhook retries). Running Cal.com on a single server with all components is fine for most organizations; the application itself is stateless, so horizontal scaling (multiple Cal.com containers behind a load balancer with a shared PostgreSQL database) is achievable. Redis provides queue reliability — if the application restarts, pending jobs (upcoming reminder emails, failed webhook retries) survive in the queue and resume processing. Total minimum RAM is 1–2 GB for a lightly loaded production instance.

For genuine high availability, the failure modes to address are: database failure (use PostgreSQL with streaming replication and a standby), application failure (run two Cal.com containers behind a load balancer), and email delivery failure (queue with Redis ensures retries on transient SMTP failures). A fully HA Cal.com setup requires Hetzner or similar infrastructure running three or more servers — primary application, replica, and database standby — at roughly $25–40/month total, still dramatically cheaper than Calendly Teams at $192/month for a 5-person team.

The scheduling tool uptime concern also argues for keeping the booking page URL stable. If your booking link is cal.yourdomain.com, a deployment or domain change requires updating that link everywhere it appears — email signatures, website CTAs, LinkedIn profiles, documentation. Plan your domain and subdomain strategy before initial deployment to avoid this.

See open source alternatives to Calendly on OSSAlt.

The SaaS-to-Self-Hosted Migration Guide (Free PDF)