Console applications

Aggregators

newsboatC++/Rust

RSS/Atom feed reader for text terminals

rss2emailPython

Converts RSS/Atom newsfeeds to email

urlwatchPython

Watch changes in webpages or command output and get notified (via e-mail, in your terminal or through various third party services) of any changes

Bookmark managers

BukuPython

Powerful bookmark management utility written in Python3 and SQLite3

Calendars & Contacts

khalPythoncalendar

Standards based CLI (console) calendar program

khardPythoncontacts

Console carddav client

VdirsyncerPythonsync

Synchronizes your calendars and addressbooks between two storages

Email

mbsyncCsync

IMAP and MailDir mailbox synchronizer

NotmuchC/C++index

Thread-based email index, search, and tagging

Clients

aercGo

Email client for your terminal

AlotPython

Terminal-based mail user agent based on the Notmuch mail indexer

MuttC

Small but powerful text-based mail client for Unix operating systems