Mac OS X Softwares to CardDAV

fruux is a robust cross-platform synchronization service designed to keep your contacts, calendars, and tasks seamlessly in sync across all your devices and applications. It offers a secure and reliable cloud platform with strong privacy focus, ideal for individuals and teams needing consistent data access and collaboration.

KMail is a powerful and flexible email client tightly integrated with the Kontact personal information manager suite. Part of the KDE ecosystem, it offers robust features for managing your email, including strong encryption options, support for multiple protocols like IMAP, POP3, and Exchange, and seamless integration with other Kontact components like the calendar and address book.

2Do is a powerful and flexible task management application offering a unique approach to organizing your life. With a focus on simplicity and customization, it provides tools for everything from quick notes to complex project management.

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.

Newton is a powerful, subscription-based email client designed for efficiency and productivity across multiple platforms. It offers a clean interface, unified inbox, and advanced features like read receipts, undo send, and integrations with popular productivity tools.