Similar to Piwigo

Enlightened Sound Daemon

Erlang (programming language)

Mule (software)

Euler Mathematical Toolbox

Exa (command-line utility)

Exaile

Expr

Falkon

Far Manager

Fast Library for Number Theory

Fetchmail

FFmpeg

Fastest Fourier Transform in the West

FindBugs

Firebird (database server)

Firestarter (firewall)

Firewalld

Flatpak

FLTK

Flutter (software)

FMSX

Foliate (software)