Open Source Credits

Időzíts is built with and on top of exceptional open-source software. We're grateful to the communities that make this possible.

We use, bundle, or redistribute the following open-source projects. Each one is listed here with its license so you know exactly what powers your scheduling.

Spam & Bot Protection

disposable-email-domains

A community-maintained blocklist of throwaway email domains used to protect booking pages from bots and bad actors. We download this list at build time and use it to screen booking submissions.

MIT
github.com/disposable-email-domains

Calendar Infrastructure

Baikal CalDAV Server

A lightweight CalDAV and CardDAV server that powers calendar storage for Időzíts. Bundled in our Docker stack and run locally on your behalf.

GPL-3.0
github.com/sabre-io/Baikal

caldav (Python)

Python client library for CalDAV, used by our API to create, read, and manage calendar events on the CalDAV server.

LGPL-2.1+
github.com/python-caldav/caldav

icalendar (Python)

Python library for parsing and generating iCalendar (RFC 5545) data. Used for building calendar event objects that sync with clients like Google Calendar and Apple Calendar.

LGPL-3.0
github.com/collective/icalendar

Frameworks & Tooling

FastAPI

The core Python web framework powering the Időzíts API. Handles booking creation, availability queries, webhooks, and all backend logic.

MIT
github.com/fastapi/fastapi

SQLAlchemy

The Python SQL toolkit and ORM used for all database operations — bookings, clients, availability rules, and billing records.

MIT
github.com/sqlalchemy/sqlalchemy

Express.js

The Node.js web framework that serves the Időzíts frontend, handles server-side rendering of booking pages, and manages authentication flows.

MIT
github.com/expressjs/express

Tailwind CSS

The utility-first CSS framework used to style the entire Időzíts interface — dashboard, booking pages, and this marketing site.

MIT
github.com/tailwindlabs/tailwindcss

This list covers libraries we directly use, bundle, or redistribute. Transitive dependencies are listed in our pyproject.toml and package.json files.