Being an avid user of RSS since the late 1990s, I have become tired of the RSS software I use disappearing when the software authors lose interest (I'm looking at you Google, Fever, etc ...). Since RSS is s daily use for me, I decided to write, and maintain, my own solution. Grapevine RSS Aggregator is the backend service. This is the "sync" engine. Run and maintain your own aggregator with an API and connect to it with a client.
QuiteRSS is a desktop news feeds (RSS/Atom) reader with a Qt interface. It's both fast and convenient to use, embeds a WebKit view, allows searching, bookmarking and filtering feed items or users. QuiteRSS also includes ad blocking, proxy support, feed update timers, a tree-grouped feed list, sound and visual notifications, OPML imports, and is fully portable.
Newspipe is a web news aggregator and reader.
JARR (Just Another RSS Reader) is a web-based news aggregator and reader.
rssgen is a command-line utility that builds an RSS feed file from multiple .html files. It reads either metatags or sets title from h1 tags, description from h2 tags and published Date from file mtime if metatags aren't available.
pyAggr3g470r is a web-based news aggregator. It can be deployed on Heroku or on a traditional server.
mobiki is a small wiki engine implemented as one PHP file. It is optimized for usage with mobile devices with limited bandwidth and for fast HTML5 content delivery. It will stay small, understandable and easy to hack - no bells, no whistles - just tin whistles. If you like, load this webpage in your mobile phone and see, how really fast it is! More about mobiki.
Sismics Reader is web-based RSS/Atom news feed aggregator implemented as Java WAR.
RSS Guard is simple (yet powerful) feed reader. It is able to fetch the most known feed formats, including RSS/RDF and ATOM. RSS Guard is developed on top of the Qt library. RSS Guard supports multiple data backends, including MySQL and SQLite.