Apps to Built-in Calendar

Sunbird was a standalone calendar application and also a Firefox extension developed by Mozilla, designed for managing events, tasks, and calendar synchronization. It aimed to provide a free and open-source solution for personal and professional scheduling needs.

Gmail, a cornerstone of Google's productivity suite, is a free, web-based email service renowned for its intelligent organization, powerful search capabilities, and integration with other Google services. Available across various platforms, it remains a leading choice for personal and professional communication.

MIDAS is a comprehensive web-based room and resource scheduling software designed for organizations of all sizes. It facilitates efficient management of spaces, equipment, and staff, streamlining the booking process and preventing conflicts.

Toshl is a comprehensive personal finance management application designed to simplify tracking expenses, income, and budgets across various accounts, including bank accounts, credit cards, and cash.

Visto is a versatile collective task dashboard designed to streamline project management, team collaboration, and workflow automation. It offers a central platform for managing tasks, tracking progress, and improving team efficiency across various business processes.

ALTO Mail is an intelligent email client designed to simplify real-life organization. It offers a unified inbox, robust features like built-in calendars, and integration capabilities to streamline communication and tasks.

Holiline Reminder is a free, multi-language calendar and organizer for Windows, designed to help users manage events, deadlines, tasks, and notes efficiently. It includes features like recurring tasks, an address book, and a built-in calendar, offering a straightforward approach to staying organized.

Kin Calendar is a sleek and intuitive calendar application designed for managing your schedule with ease. It offers seamless integration with popular services like Google Calendar and Facebook, supports multiple accounts, and includes features for reminders, events, and task management, all within a clean, ad-free interface.

AOL Mail is a free web-based email service offering reliable communication tools, generous storage, and integrated features like calendar and cloud storage, suitable for individuals and small businesses seeking a straightforward email solution.

VueMinder Calendar is a comprehensive calendar and task management application for Windows, designed to help users organize their schedules and boost productivity. It offers a wide range of features including robust synchronization options, customizable views, and advanced reminder capabilities, making it suitable for both personal and professional use.

Posteo is a privacy-focused, secure email service based in Germany, offering paid accounts with strong encryption and transparency features. It emphasizes user data protection and operates on a green energy infrastructure.

todoyu is a comprehensive web-based collaboration and project management solution designed for teams and businesses of all sizes. It integrates essential tools like task management, time tracking, resource planning, a shared calendar, and client interaction features into a single platform.

Jorte is a comprehensive calendar and organizer application designed to help users manage their schedules, tasks, and notes efficiently across multiple devices. It offers a flexible and customizable interface to suit individual preferences and integrates with popular calendar services.

Kontact is a comprehensive personal information management suite from KDE combining email, contacts, calendar, tasks, and news in one integrated application. It offers robust synchronization options and supports various protocols.

Open365 is a comprehensive, open-source productivity suite offering cloud storage, office applications, and communication tools. Built upon a foundation of open-source technologies like KDE, Seafile, and LibreOffice, it provides a robust alternative to proprietary solutions, emphasizing privacy and control.

Email.biz offers a secure and privacy-focused email service designed for businesses and individuals prioritizing data protection and generic domain identities. It provides essential communication tools including encrypted email, calendar, and contact management, with integrations for enhanced productivity.

Contentools is an all-in-one content marketing platform designed to streamline the entire content lifecycle for growing businesses, from ideation and creation to distribution and analysis.

ColorNote is a lightweight and intuitive notetaking and checklist application for Android. It allows users to quickly create and organize notes and lists with color-coding, syncing, and simple features for everyday productivity.

Kolab Now is a comprehensive, secure, and privacy-focused web-based email and groupware suite. Built entirely on free and open-source software, it offers a full range of collaborative tools including email, calendar, contacts, and document management, prioritizing user data ownership and security.

Nylas Mail, an extensible open-source email client, offers a unified inbox, robust search, and calendar integration. It supports multiple accounts and provides features like email tracking and undo send, aiming to enhance productivity and email management for users.

EssentialPIM is a versatile personal information manager designed to help you organize your life. It allows you to manage appointments, tasks, notes, contacts, passwords, and more, all within a single, customizable application available for desktop and mobile platforms.

OpenMailBox is a free, privacy-focused email hosting service emphasizing security and protecting user data. It provides a webmail interface along with support for standard email protocols.

Windows Live Mail was Microsoft's free email client that succeeded Outlook Express and Windows Mail. It offered a familiar interface for managing multiple email accounts, calendars, and contact lists, integrating with other Windows Live services.

Day One is a popular journaling application available on macOS, iOS, and Android. It provides a simple and elegant interface for capturing daily thoughts, experiences, and memories with rich media support.

GMX Webmail provides a reliable and feature-rich free email service. With strong privacy features, integrated cloud storage, and tools like a calendar and mail collector, it offers a comprehensive suite for managing digital communication and files.

Yahoo! Mail is a long-standing web-based email service offering various plans for personal and business use. It provides essential email functionalities along with integrated features like chat and calendar.

Yandex.Mail is a robust and feature-rich free email service offering generous storage, strong privacy features, and seamless integration with other Yandex services. It provides comprehensive support for various protocols and tools for efficient email management for both personal and professional use.

Buffer is a comprehensive social media management platform designed to help individuals and businesses schedule posts, analyze performance, and engage with their audience across various social networks.

Apple Calendar is a personal calendar application developed by Apple Inc., designed to seamlessly integrate with your Apple ecosystem whether you are on macOS or iOS. It allows you to manage your schedule, appointments, and events efficiently, synchronizing across all your devices.

Lightning is a comprehensive calendar and task management add-on for Mozilla Thunderbird and Seamonkey, designed to integrate seamlessly with email. It offers robust features for scheduling, task tracking, and synchronization with various online calendar services, enhancing productivity directly within your email client.