Use REAPER's built-in JS scriptable plug-in engine to write real, high-quality effect plug-ins, with 64-bit audio resolution and sample-accurate MIDI.

JS uses a C-like scripting language that you can compose and edit in any text editor. REAPER includes a JS editor and debugger that opens with a click on any JS plug-in window. You can edit and compile changes to JS plug-ins without even stopping audio playback.
One of REAPER's greatest assets is its creative, helpful, and engaged user community. That community includes talented developers of plug-ins and extension code.

REAPER users have created literally thousands of JS audio and MIDI plugins, many of which are included with the REAPER installer, and many more of which can be found in the REAPER user forum or on various user web sites. These plug-ins require no installation: simply copy the plain text file containing the JS script into your REAPER/Effects directory.

Third-party developers have also created interesting and useful REAPER extensions. These add-ons integrate directly into REAPER, to provide new custom features and actions that are just as accessible as any built-in REAPER functionality.
REAPER's open SDK allows direct integration of third-party extensions, which provide additional features that can be used within REAPER. Extensions are a vital part of the workflow of many REAPER power users.

Extensions are written in C++, using the REAPER extension API.

Popular REAPER add-ons (created by third-party developers, not by us) include: