Top 9 Open-Source Alternatives to ProtonCalendar

Product categories

APIs Appointments and Scheduling Calendar Calendar And Scheduling Email Email Clients Email Management Encryption Enterprise Communication Hosted Email SMTP Server Self-hosted Email

Summary

The top open-source alternatives to ProtonCalendar are Nextcloud Calendar, Simple Calendar, and SOGo. One of the criteria for ordering this list is the number of mentions that products have on reliable external sources. You can suggest additional sources through the form here.

Nextcloud Calendar Landing Page
1

Nextcloud Calendar

The Calendar app is a user interface for Nextcloud's CalDAV server.
Pricing:
- Open Source
#Calendar #Appointments and Scheduling #Email 4 social mentions
Simple Calendar Landing Page
2

Simple Calendar

A simple calendar with events (optional recurring and reminders), week numbers and a customizable...
Pricing:
- Open Source
#Calendar #Appointments and Scheduling #Email 99 social mentions
SOGo Landing Page
3

SOGo

SOGo is groupware server with a focus on scalability and open standards.
Pricing:
- Open Source
#Email #Email Clients #Self-hosted Email 1 social mentions
Rainloop Landing Page
4

Rainloop

RainLoop is a web based email client.
Pricing:
- Open Source
#Email #Email Clients #Email Management
Tutanota Landing Page
5

Tutanota

Get your encrypted mailbox for free.
Pricing:
- Open Source
#Email #Email Clients #Enterprise Communication 177 social mentions
Roundcube Landing Page
6

Roundcube

Web-based IMAP email client
Pricing:
- Open Source
#Email #SMTP Server #Email Clients 16 social mentions
Calendar Lock PEA Landing Page
7

Calendar Lock PEA

Calendar Lock PEA is an encrypted desktop calendar with a day, week and month view. The shown calendars are never stored unencrypted on your disk, but exist only in the RAM. Platform-independent, Open Source, no installation or registration required.
Pricing:
- Open Source
#Calendar #Appointments and Scheduling #Encryption
Cal.com Landing Page
8

Cal.com

Cal.com (formerly Calendso) is the open source Calendly alternative.
Pricing:
- Open Source
#APIs #Open Source #Calendar And Scheduling 53 social mentions
Mailpile Landing Page
9

Mailpile

Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.
Pricing:
- Open Source
#Email #Email Clients #Email Management