The framework is also known as F3::PHP or just F3.

F3 supports NoSQL off-the-shelf.

The framework has a mini-ORM for SQL databases like MySQL, SQLite, MSSQL/Sybase, dblib and PostgreSQL.

Here are some key features of "Fat-Free Framework":

· Fast and clean template engine,
· Dynamic XML sitemaps,
· Atom/RSS feed reader,
· CAPTCHA, thumbnail and fake image generator,
· On-the-fly Javascript/CSS compressor,
· Identicons,
· User authentication,
· OpenID (consumer),
· Custom logger,
· Network diagnostics,
· Lightweight subsets of PHP's mb_string and intl extensions,
· SMTP over SSL/TLS,
· API wrappers for Google, Twitter, Yahoo! and Akismet,
· Tools for communicating with other servers,
· ZIP archive manager.