DAVx⁵ is an open-source CalDAV/CardDAV suite and sync app for Android. You can also access your online files (WebDAV) with it.

Robust and type-safe date and time calculations for Swift

A simple python library to interact with Microsoft Graph and Office 365 API

📆 Calendar app for Nextcloud

Worldwide holidays and workdays computational toolkit.

Synchronize RSS, contacts, calendars, tasks and more without a server

A self-hosted calendar and scheduler server.

Get a date with JavaScript! A datepicker with no dependencies.

WebDAV, CALDAV, and CARDDAV client for Nodejs and the Browser

Android app to sync contacts, calendars and tasks without a server using DecSync

A customisable, multilingual calendar with 3 different sizes. With LaTeX.

KosherJava Zmanim API / Library

A simple PHP class to generate calendars. Easy to populate, the calendar shows events by passing in an array.

Tools for working with recurrence rules, holidays, and calendars

Timetrack - a simple command line program for analysing your own calendar data.

Date range picker, two-pane calendar with custom rendering and multiple selection. The tDatepicker more than 35 pretty options and many methods help you change date, getDate, update when you need.

🚴 Making bike racing in USA "a better place" or "great again"

JavaScript library for working with Date and Time in different calendars and locals

IFSC Climbing iCal Calendar Builder

Synchronize your Airbnb, Booking.com, and other iCal rental calendars on your own server - easy and free