| APNG Assembler | assemble APNG animation from PNG/TGA image sequence | https://sourceforge.net/projects/apngasm | Other | |
| APNG Optimizer | optimize APNG animated images | http://apng.sourceforge.net | Other | |
| APQ | Ada95 Database Library | http://web.archive.org/web/20110609012236/http://framework.kow.com.br/ | Other
GPLv2orlater | |
| APQ PostgreSQL | PostgreSQL impementation for the APQ database bindings | http://web.archive.org/web/20110609012236/http://framework.kow.com.br/ | Other
GPLv2orlater | |
| APSR | TCP/IP packet sender to test firewalls and other network applications | http://www.aa-security.de/ | GPLv2 | |
| APScheduler | In-process task scheduler with Cron-like capabilities | https://pypi.org/project/APScheduler | Other | |
| APacheDEX | Compute APDEX from Apache-style logs | http://git.erp5.org/gitweb/apachedex.git | GPLv2orlater
Expat | |
| ARChon Packager | ARChon Packager (formerly Chrome APK Packager) is a convenient way to produce Chrome ARChon Custom Runtime packages directly from your phone. | https://github.com/bpear96/ARChon-Packager | GPLv3orlater | |
| ARChon Runtime for Chrome | Run Android Apps in Chrome in OS X, GNU/Linux and Windows | https://archon-runtime.github.io/ | | |
| ARDEN | specificity control for read alignments using an artificial reference | http://sourceforge.net/projects/arden/ | Other | |
| ARandR | Simple visual front end for XRandR | http://christian.amsuess.com/tools/arandr/ | GPLv3orlater | |
| ARts | Framework for developing modular multimedia applications | https://web.archive.org/web/20060106015222/http://www.arts-project.org/ | LGPLv2orlater | |
| ASCEND | A flexible modelling environment for hard engineering and science problems. | http://ascend.cheme.cmu.edu/ | GPLv2 | |
| ASEPRITE | sprite and pixel art editor | http://www.aseprite.org/ | Zlib
Other
GPLv2orlater
BSD 3Clause | |
| ASIS | Ada Semantic Interface Specification | http://docs.adacore.com/asis-docs/html/asis ug/asis ug/introduction.html#introduction | GPLv3orlater | |
| ASN.1 Compiler | ASN.1 compiler for C | http://asn1c.sourceforge.net | GPLv2orlater
BSD 2Clause | |
| ASPSeek | Search engine | http://www.aspseek.org/ | GPLv2orlater | |
| AST | Handle World Coordinate Systems in Astronomy (main shared lib) | http://www.starlink.ac.uk/ast | PublicDomain
Other | |
| AT Emulator | Emulate a communication device, like a modem | https://www.celersms.com/at-emulator.htm | | |
| AT1 | JACK autotuner | http://kokkinizita.linuxaudio.org/linuxaudio/ | GPLv2orlater | |
| ATC-pie | Air traffic control simulation (solo and multi-player) | https://sourceforge.net/projects/atc-pie | GPLv3 | |
| ATK | The Gnome accessibility toolkit | https://developer.gnome.org/atk/ | LGPLv2orlater | |
| ATLAS | Generates high-performance mathematical libraries | http://math-atlas.sourceforge.net/ | BSD 3Clause | |
| ATM SAR Library (SARLib) | ATM Segmentation and Reassembly Library. | http://sarlib.sourceforge.net/ | GPLv2orlater | |
| ATOS | Manage projects, generate invoices, and estimate your taxes | https://github.com/jbelelieu/atos | AGPL-3.0 | |
| ATSLog | A web-oriented interface for collecting, viewing and analysing calls for various types of PBXs. | https://sourceforge.net/projects/atslog.berlios/ | GPLv2orlater | |
| AUnit | AUnit, a unit testing framework for Ada: documentation | http://libre.adacore.com/libre/ | GPLv3orlater | |
| AVFS | Lets programs look at archived files without having to recompile them | http://www.inf.bme.hu/~mszeredi/avfs/avfs.html | GPLv2 | |
| AVInfo | Displays audio/video header information | http://shounen.ru/soft/avinfo/ | GPLv2orlater | |
| AVRA | assembler for Atmel AVR microcontrollers | http://avra.sourceforge.net | Other
GPLv2orlater | |
| AVbin | a thin wrapper around FFmpeg. | https://avbin.github.io/AVbin/Home/Home.html | GPLv2orlater
LGPLv3orlater | |
| AVideo | A powerful, 100% libre video and audio downloader for GNU/Linux | https://notabug.org/GPast/avideo | GPLv3orlater | |
| AWF | Web framework for a CMS/portal/online group | http://web.archive.org/web/20120917065920/http://www.awf-cms.org/ | GPLv2orlater | |
| AWOL | In/out board | http://sourceforge.net/projects/awol/ | GPLv2 | |
| AWS SDK for PHP | software development kit to build solutions for Amazon | http://aws.amazon.com/sdkforphp/ | Other
Expat | |
| AWStats | Generates and displays Web server statistics graphically | http://awstats.sourceforge.net/ | GPLv2orlater | |
| AZR3 | drawbar organ simulator | http://ll-plugins.nongnu.org/azr3/ | GPLv2 | |
| Aac-tactics | Coq tactics for reasoning modulo AC (theories) | http://sardes.inrialpes.fr/~braibant/aac tactics/ | LGPLv3 | |
| Aafigure | ASCII art to image converter. | https://launchpad.net/aafigure | BSD 3Clause | |
| Aalib | ASCII art library | http://aa-project.sourceforge.net/aalib/ | LGPL | |
| Aap | The Aap program executes recipes. It is a kind of super-make program. | http://www.a-a-p.org/ | ISC
Expat
GPLv2 | |
| Aardvark Shellutils | Three utilities to make working with shell scripts easier | http://www.laffeycomputer.com/shellutils.html | GPLv2orlater | |
| Aasm | Advanced assembler. | https://savannah.nongnu.org/projects/aasm/ | GPLv3orlater | |
| AbGate | LV2 noise gate plugin | http://abgate.sourceforge.net | Other
LGPLv3 | |
| Abacas | Algorithm Based Automatic Contiguation of Assembled Sequences | http://abacas.sourceforge.net/ | GPLv2orlater | |
| AbanteCart - Open Source Ecommerce Solution | AbanteCart is a free software shopping cart or ecommerce platform for small to medium size business. It is designed, built and supported by experienced enthusiasts that are passionate about their work and contribution to the rapidly evolving eCommerce industry. AbanteCart is powered with a robust and expandable core platform, state of the art feature set and a efficient user interface. | http://www.abantecart.com | | |
| Abbrev | Get unique abbreviations for a set of strings - Node.js module | https://github.com/isaacs/abbrev-js | Expat | |
| Abbrev-js | Like ruby abbrev module, but for Node.js | https://github.com/isaacs/abbrev-js | Expat | |
| Abc2ps | Typesetting program for ABC format | http://www.ihp-ffo.de/~msm/ | GPLv2orlater | |
| Abcde | Rips, encodes, and tags CDs with one command | http://code.google.com/p/abcde/ | Perl | |
