A list of known Free audio plugins (for use with e.g.  Ingen).

LV2

• Calf  http://calf.sourceforge.net/
• ll-plugins  http://ll-plugins.nongnu.org/
• SWH  http://plugin.org.uk/lv2/
• zynadd  http://home.gna.org/zyn/

LADSPA

Good

• AMB  http://kokkinizita.net/linuxaudio/index.html
• Blepvco  http://www.smbolton.com/linux.html
• Blop  http://blop.sf.net
• CAPS  http://quitte.de/dsp/caps.html
• CMT  http://www.ladspa.org/cmt/
• FIL  http://kokkinizita.net/linuxaudio/index.html
• FOO  http://www.studionumbersix.com/foo/
• MCP  http://kokkinizita.net/linuxaudio/index.html
• NJL  http://www.ecs.soton.ac.uk/~njl98r/code/ladspa/njl-plugins/
• Omins  http://www.nongnu.org/om-synth/omins.html
• REV  http://kokkinizita.net/linuxaudio/index.html
• SWH  http://plugin.org.uk/
• TAP  http://tap-plugins.sourceforge.net/
• VCF  http://www.suse.de/~mana/ladspa.html
• VCO  http://kokkinizita.net/linuxaudio/index.html
• VLevel  http://vlevel.sourceforge.net/
• Vocoder  http://www.sirlab.de/linux/download_vocoder.html
• WASP  http://linux01.gwdg.de/~nlissne/wasp/index.html (maintainer wanted!)
• Nova  https://tim.klingt.org/nova/download/nova_filters-0.2.tar.bz2

Outdated/Broken

• Clipper  http://quitte.de/dsp/spiced-12AX7.html
• Lemux  http://lumatec.be/joost/
• Preamp  http://quitte.de/dsp/preamp.html
• PVOC  http://quitte.de/dsp/pvoc.html
• Unmatched  http://quitte.de/dsp/unmatched.html
• Q2Ladspa  ftp://mustec.bgsu.edu/pub/linux/q2ladspa.tar.gz

DSSI

• Examples  http://dssi.sf.net
• Lars' Plugins  http://ll-plugins.sf.net
• WhySynth  http://home.jps.net/~musound/whysynth.html
• X-Y Controller  http://www.skynet.ie/~jmmcd/software/xy-controller-dssi.tar.gz