LV2 (LADSPA Version 2) is a set of royalty-free open standards[2] for music production plug-ins and matching host applications.

LV2 succeeds the more limited Linux Audio Developer's Simple Plugin API (LADSPA) standard and replaces the Disposable Soft Synth Interface (DSSI) plugin infrastructure ("LADSPA for instruments"), adding abilities such as MIDI capability, custom UIs, and a system allowing extensibility of the initial standard.

[7] Software that can host LV2 plugin "bundles" includes Ardour, Ingen, Carla (of KXStudio), Qtractor, Traverso DAW,[8] Harrison Mixbus,[9] MusE, Audacity,[10] Ecasound, FFmpeg, Guitarix, the GStreamer framework and DJing software Mixxx, with currently partial support in LMMS and REAPER.

[16] Beyond the core specification there are 21 official extensions providing support for host options, plugin presets, time and units, port buffers, properties, groups and parameter labels, for sending MIDI, patches, UI events and more.

[17] There are various third-party extensions for supporting expressive events, OSC, and MOD Devices specific hardware and software, with three in the KXStudio LV2 Namespace.

This is generally useful because a plugin is usually run in the real-time audio thread of an application, and hence cannot do any non-real-time safe operations (disk-accesses, system calls, etc.).

To make it easy for the plugin to achieve its goals (e.g.: load a file from disk), the host can provide a worker thread.