File alteration monitor

http://oss.sgi.com/projects/fam/

Programming font, designed with functionality in mind

https://fontlibrary.org/en/font/fantasque-sans-mono

Serif based on the work of a famous Czech-American type designer

https://www.theleagueofmoveabletype.com/fanwood

Standard set of Unicode Persian fonts

http://www.farsiweb.ir/wiki/Persian_fonts

Collection of GStreamer modules and libraries for videoconferencing

https://www.freedesktop.org/wiki/Software/Farstream/

version of JDK's `jar' command written entirely in C

http://fastjar.sourceforge.net/

Accuracy-focused XAudio reimplementation

https://fna-xna.github.io/

FastCGI Development Kit

http://www.fastcgi.com/

CUI-based file and directory management tool

https://hp.vector.co.jp/authors/VA012337/soft/fd/

Port of the Fraunhofer FDK AAC Codec Library

https://sourceforge.net/projects/opencore-amr/

Image viewer that utilizes Imlib2

https://feh.finalrewind.org/

Batch mail retrieval utility for IMAP/POP3/ETRN/ODMR

https://www.fetchmail.info/

Realtime audio/video encoder/converter and streaming server

http://ffmpeg.org/

Realtime audio/video encoder/converter and streaming server

http://ffmpeg.mplayerhq.hu/

Lightweight video thumbnailer that can be used by file managers

https://github.com/dirkvdb/ffmpegthumbnailer

FFmpeg-based source library and VapourSynth plugin

https://github.com/FFMS/ffms2

Utility to recover UFS2 filesystems

https://BSDforge.com/projects/sysutils/ffs2recov/

Fast C routines to compute the Discrete Fourier Transform

http://www.fftw.org/

Fast Discrete Fourier Transform (Single Precision C Routines)

http://www.fftw.org/

Fast Discrete Fourier Transform (Long Double Precision C Routines)

http://www.fftw.org/

Integrated benchmark program

http://tromp.github.io/c4/fhour.html

Small, efficient C++ GUI library designed for games

http://fifengine.net/

Narrow monospaced fonts

https://fontlibrary.org/en/font/fifteen

Tools to convert Xfig .fig files

https://en.wikipedia.org/wiki/Xfig

Archive manager for zip files, tar, etc

https://wiki.gnome.org/Apps/FileRoller

Tcl/Tk-based filemanager with FTP capabilities

https://sourceforge.net/projects/filerunner/

Fast and reliable cross-platform FTP, FTPS, and SFTP client

https://filezilla-project.org/

Finch multi-protocol messaging client (Console UI)

https://www.pidgin.im/

GNU find utilities

https://www.gnu.org/software/findutils/

Sans-serif, monospaced, and code typeface for small screens

https://bboxtype.com/typefaces/FiraSans/

Monospaced font with programming ligatures derived from Fira

https://github.com/tonsky/FiraCode

Expanded version of Fira Sans with support for additional languages

https://bboxtype.com/typefaces/FiraGO/

Firebird-2 database client

https://sourceforge.net/projects/firebird/

Firebird-2 relational database (server)

https://sourceforge.net/projects/firebird/

Firehol ip list downloader

http://iplists.firehol.org/

Remote firewall auditing tool

http://www.packetfactory.net/firewalk/

Expand / when the system first boots

Update the system using midnightbsd-update when it first boots

Install packages when the system first boots

User friendly command line shell

https://fishshell.com/

Form a line of 5 or more colored balls

https://wiki.gnome.org/Five%20or%20more

Patch making it possible to embed PNGs into RTFs

Free lossless audio codec

https://www.xiph.org/flac/

Backup content from any volume to a tarball

https://github.com/laffer1/flashback/

Fast lexical analyzer generator

https://github.com/westes/flex

Small run-time speech synthesis engine

http://www.festvox.org/flite/

Manage locks from shell scripts

https://www.kernel.org/pub/linux/utils/util-linux/

Floating point benchmark to give your MFLOPS rating

http://performance.netlib.org/performance/html/flops.html

Suite of tools and library to work with netflow data

https://github.com/5u623l20/flow-tools/

Cross-platform C++ graphical user interface toolkit

https://www.fltk.org/