Motif X11 Toolkit (industry standard GUI (IEEE 1295))

https://motif.ics.com/

Clean and modern sans-serif typeface

https://www.opensans.com

Open VMware tools for MidnightBSD VMware guests

https://github.com/vmware/open-vm-tools

3D positional spatialized sound library

http://www.openal.org/

Software implementation of the OpenAL specification

http://kcat.strangesoft.net/openal.html

Chemical toolbox designed to speak the many languages of chemical data

https://openbabel.org/wiki/Main_Page

Optimized BLAS library based on GotoBLAS2

https://github.com/xianyi/OpenBLAS

Small, fast, standards compliant, extensible window manager

http://openbox.org/

Open Crypto Development Kit

http://www.gnutls.org/

Open Computing Language (OpenCL) specifications V3.0 (header files)

https://github.com/KhronosGroup/OpenCL-Headers/

OpenCORE implementation of AMR Narrowband & Wideband speech codec

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

Middleware framework for smart card terminals

https://github.com/OpenSC/openct

Open Source Computer Vision library

https://www.opencv.org/

DKIM library and milter implementation

http://opendkim.org/

High dynamic-range (HDR) image file format

https://github.com/AcademySoftwareFoundation/openexr/

Enterprise instant messaging server

https://www.igniterealtime.org/projects/openfire/index.jsp

Fast and powerful code search and cross-reference engine

http://opengrok.github.io/OpenGrok/

Cisco implementation of H.264 codec

https://www.openh264.org/

Complex IPMI management software

http://openipmi.sourceforge.net/

Object-oriented SGML/XML parser toolkit and DSSSL engine

http://www.netfolder.com/DSSSL/

OpenJDK 11 FreeBSD binary

http://openjdk.java.net/

OpenJDK 13 FreeBSD binary

http://openjdk.java.net/

OpenJDK 18 FreeBSD binary

http://openjdk.java.net/

OpenJDK 7 FreeBSD binary

http://openjdk.java.net/

OpenJDK 8 FreeBSD binary

http://openjdk.java.net/

Open-source JPEG 2000 codec

https://www.openjpeg.org/

Open-source JPEG 2000 codec

https://www.openjpeg.org/

Open source LDAP client implementation

https://www.OpenLDAP.org/

Open source LDAP client implementation with SASL2 support

http://www.OpenLDAP.org/

Open source LDAP server implementation

https://www.OpenLDAP.org/

Open Multi-Processing runtime for LLVM/Clang

http://openmp.llvm.org/

High Performance Message Passing Library

http://www.open-mpi.org/

Software to control a multitude of (a)RGB devices

https://openrgb.org

Implementation of rsync with a BSD (ISC) license

https://github.com/kristapsdz/openrsync

Libraries and utilities to access smart cards

https://github.com/OpenSC/OpenSC/wiki

Full-text search engine for Java

http://opensearch.org

Open-source implementation of the Service Location Protocol

http://www.openslp.org/

This package is a collection of SGML/XML tools called OpenSP

http://openjade.sourceforge.net/doc/

Graphical password applet for entering SSH passphrase

http://www.jmknoble.net/software/x11-ssh-askpass/

The portable version of OpenBSD's OpenSSH

https://www.openssh.com/portable.html

TLSv1.3 capable SSL and crypto library

https://www.openssl.org/

UPS daemon for some Belkin UPS's

http://frmb.org/openupsd.html

Secure IP/Ethernet tunnel daemon

https://openvpn.net/community/

Optimizer for PNG files

http://optipng.sourceforge.net/

IETF audio codec

https://opus-codec.org/

Opus playback library

https://www.opus-codec.org/

Geometric sans-serif typeface intended for display purposes

https://github.com/theleagueof/orbitron

Library and toolset to operate arrays of data

https://gstreamer.freedesktop.org/projects/orc.html

Scriptable screen reader

http://live.gnome.org/Orca

Real-time Transport Protocol (RTP) library

https://www.linphone.org/technical-corner/ortp.html