You can download and install plug-ins or libraries to add extra functionality to Audacity. Plug-ins can give you extra effects, or more audio generation and analysis capability. Adding libraries can allow you to import or export additional audio formats.
Installation instructions for plug-ins are provided in the Audacity manual. Note that the instructions vary according to platform (Windows / Mac / Linux) and the type of plug-in.
Audacity has built-in support for Nyquist effects on all operating systems. You can download additional Nyquist plug-ins, or create your own using the Nyquist programming language. Nyquist code can be conveniently tested using “Nyquist Prompt” under the Effect menu.
Audacity has built-in support for LV2 plug-ins, which are an extensible successor of LADSPA effects. LV2 plug-ins are mostly built for Linux, but Audacity supports LV2 on all operating systems. To install LV2 plug-ins, place them in the system LV2 location then use the Plug-ins Manager to enable the new plug-ins as in the plug-in installation instructions.
Audacity can load VST effects (but not VST instruments) on all operating systems. The VST Enabler is no longer required. Install the VST effects to the Audacity Plug-Ins folder on Windows, to ~/Library/Application Support/audacity/Plug-Ins on OS X/macOS or to system locations. Then use the Plug-ins Manager to enable the new plug-ins as in the plug-in installation instructions above.
VST effects can be found on many plug-in sites such as:
Audio Unit Plug-ins
On Mac OS X only, you can add Audio Unit plug-ins to the system plug-in directories (Audacity will not recognize any Audio Units in its own “plug-ins” folder). Then use the Plug-ins Manager to enable the new plug-ins and any required Apple Audio Units as in the plug-in installation instructions above.
Experimental modules offer a further way to extend Audacity with new features.
The FFmpeg import/export library allows Audacity to import and export many additional audio formats such as AC3, AMR(NB), M4A and WMA, and to import audio from video files. Audacity 2.0.6 and later requires FFmpeg 1.2 to 2.3.x (or libav 0.8 to 0.10.x). To install FFmpeg, please read our FFmpeg FAQ.