Best open-source alternatives to Calendly

Cal.diy is a community-maintained, MIT-licensed scheduling platform intended for people who want to run their own instance. It is presented as the open-source community edition of Cal.com, with proprietary and enterprise-only components removed. The README emphasizes that it is meant for self-hosting rather than managed use, and that it is best suited to users comfortable handling servers, databases, and sensitive configuration. The project is built with modern web tooling including Next.js, tRPC, React, Tailwind CSS, Prisma, and Daily.co. Setup is documented for local development and self-hosting, including Node.js, PostgreSQL, Yarn, environment variables, and database migrations. It also provides a Docker-based quick start (`yarn dx`) that boots a local Postgres instance and seeds several test accounts, including an admin user, to make development and evaluation easier.

Cal.diy is the community edition of Cal.com, presented as a fully open-source scheduling platform intended for people who want to run their own scheduling stack. The README emphasizes that it is self-hosted only, aimed at personal and non-production use, and that it removes enterprise/commercial code from the upstream project. It is positioned for users who want full control over scheduling infrastructure without relying on a hosted service or license key. The project is built with Next.js, tRPC, React, Tailwind CSS, Prisma, and Daily.co. Getting started requires a Node.js runtime, PostgreSQL, and Yarn, with options for local development via Docker Compose, a Gitpod workspace, or manual setup. The README also documents seeded test accounts, database migration/deployment commands, and environment-variable configuration for local and production-style setups.

Rallly is a self-hostable scheduling tool designed to help people organize group meetings without long email threads. It lets users create meeting polls so participants can indicate when they are available, making it easier to choose a date and time that works for everyone. The project is positioned for friends, colleagues, and teams that need a simple way to coordinate events. The application is built with Next.js, Prisma, tRPC, and TailwindCSS, and the README includes instructions for running a local development environment. It relies on a Docker-based database setup for local installation, and the project points users to separate self-hosting documentation and configuration options for running their own instance. The code is released under the GNU AGPLv3 or later, indicating an open-source, self-hosted deployment model.

Indico is a web-based event management system designed for organizing conferences, meetings, and related activities. It is aimed at institutions and communities that need a feature-rich platform for managing event content, registrations, reviews, schedules, rooms, and participant materials. The project emphasizes extensibility through plugins and covers a broad workflow from call for abstracts and abstract reviewing to registration forms, payment integration, paper reviewing, timetable management, badge printing, and room booking. The README also points users to a sandbox for trying the software and to documentation for installation and further details.

LibreBooking is an open-source resource scheduling system built for organizations that need to manage reservations for shared resources. It presents a flexible, mobile-friendly web interface and includes support for bookings, waitlists, quotas, reporting, and theming. The project appears aimed at self-hosters and administrators who want a configurable scheduling tool with role-based access control and integration options. It can be installed manually on a typical PHP/MySQL stack or deployed with Docker, and the README points to separate documentation for installation, configuration, developer notes, APIs, OAuth2, and SAML.

Easy!Appointments is a self-hosted appointment scheduling web application aimed at businesses and service providers that need to let customers book appointments online. The project emphasizes customization, making it suitable for different workflows and commercial use while remaining deployable on a server alongside an existing website and database. It includes core scheduling tools for managing customers, appointments, services, providers, working plans, and booking rules. The README also highlights Google Calendar synchronization, email notifications, and a translated interface. Installation is done by copying the source to a server and configuring it for a PHP/MySQL stack, with local development supported via Node.js, npm, and Composer.

Easy!Appointments is an open source web application for appointment scheduling that is intended to be installed on a server and used as part of an existing website. It is aimed at businesses or service providers that need customers to book appointments through a web interface, with support for managing appointments, providers, and booking rules. The project emphasizes self-hosted deployment and practical integrations, including synchronization with Google Calendar and email notifications. The README also notes that it can share an existing database and fit into a single server folder, suggesting it is designed for straightforward integration into an existing web stack rather than a managed cloud service.

Bitpoll is a web application for creating and running polls about dates, times, and general questions. It is a rewritten version of the Dudel project and is built with Django on the backend. The project is aimed at users who need simple scheduling and question polling with flexible participation rules. It supports anonymous or named votes, optional registration before voting, private event polling for invited participants, and poll URLs that can be chosen manually or generated automatically. Bitpoll can be deployed either with Docker or by manually cloning the repository and installing dependencies in a Python virtual environment. The README also describes production use with LDAP login, uWSGI, and Sentry-based error reporting.

calrs is an open-source scheduling platform written in Rust for people and teams that want to self-host their booking workflow. It lets users connect one or more CalDAV calendars, define bookable meeting types, and share booking links for public, private, team, or dynamic-group scheduling. The project is aimed at users who want an alternative to hosted scheduling services while keeping control over their stack. Its README emphasizes CalDAV-based availability checks, booking confirmations, rescheduling, team management, admin controls, and a web dashboard for managing sources, event types, and bookings. The software is positioned as lightweight and self-hostable, with no Node.js, no PostgreSQL, and no subscription required.

Assets management and booking for small/medium companies.