Open Source Apps with 'Calendar View' feature for Windows

Cross-platform email client providing POP/IMAP support, robust filtering, multiple accounts, and chat. Extendable via add-ons with RSS/Atom, etc.

On-premises file sync, universal access, integrated collaboration, real-time communication with privacy and data control focus.

Local-first, privacy-focused notebook supporting Markdown and Org mode, offline use, encrypted backup, extensible with plugins, and more.

Open-source app tracking time on devices, maintaining privacy and versatility, with features like productivity insights, Pomodoro timers, and local data storage.

Free multi-platform software for task management, time tracking, and personal project management. Seamless integration with Jira, GitHub, and GitLab.

End-to-end encrypted app for email, calendar, and contacts, requiring no personal data, with open source code and quantum-resistant security.

The original trilium is transfered to this repo by its owner and the app continues to develop here as stated here: https://github.com/TriliumNext/Trilium

Transform data with an open-source interface using relational databases and Python engines. Collaborate in real-time with custom permissions for security.

TimeScribe lets you effortlessly start, stop, and pause your work time with just a click, ensuring a straightforward time tracking experience. The app provides an intuitive dashboard to monitor your daily activities, including breaks, and allows you to customize your weekly work...

Integrates enterprise resource planning, CRM, and more, eliminating the need for multiple software with open-source solutions developed in Python.

Org mode is for keeping notes, maintaining TODO lists, planning projects, and authoring documents with a fast and effective plain-text system.

WeekToDo is a free and Open Source minimalist weekly planner. With WeekToDo you can start improving your productivity by defining and managing your week and your tasks in an easy and intuitive way.

RedNotebook is a graphical diary and journal helping you keep track of notes and thoughts. It includes a calendar navigation, customizable templates, export functionality and word clouds. You can also format, tag and search your entries.

acreom is an actionable personal knowledge base for developers. It helps developers ship faster by centralizing personal and team context in one place.

Experience Condution, a powerful yet incredibly simple check-list application that supports your needs from study, business, and life. Bring Condution with you across the Globe and let it be your second brain — so you can focus on living your best life.

All you need in a team collaboration tool dedicated to small efficient teams. Chat, notes, drive, online collaborative edition, calendars, news, spaces, notifications...

A simple program for managing daily annotations, attachments and attributes.

Knowledge is a tool for saving, searching, accessing, exploring and chatting with all of your favorite websites, documents and files.

TowDow is an open-source, cross-platform application designed for small and mid-sized teams to manage tasks, projects, and processes in one place. It allows you to create projects, assign tasks, set deadlines, and follow progress in real time across desktop and mobile devices.

Adaptive management suite integrating project, IT service, and source code workflows for technology teams, featuring time tracking, document, and issue management.

Idaesbasic - An all in one project manager that stores everything in files directly into your project!

ProjeQtOr (formely Project'Or RIA) is an open source Project Management Software, gathering in a single tool every functionality needed to organize your projects.

Power Planner is the ultimate homework planner for students, featuring online sync with iOS and Android apps, grade calculation, live tiles, automatic reminders, and more.

No-Fuss Time Management App .

Stategr helps you maximize your productivity, giving you the quickest and most effective way to time-box your day with strategies.

A strategy consists of activities and sessions.

An Open Source minimalist eye care reminder & Break Timer app for Windows, macOS, and Linux.