Plugins That Knock, also operating as Knock Audio, is an audio plugin developer founded by hip-hop producer and sound designer DECAP. The company grew out of DECAP's Drums That Knock sample pack series, extending the same drum-focused production philosophy into software effects aimed at producers working on modern hip-hop, trap, and pop.

Its flagship product is KNOCK, a multi-effect plugin built around a chain of five modules — Punch (transient shaping), Saturate (harmonic distortion with loudness compensation), Sub (sub-frequency layering tuned to kick drums), Air (top-end enhancement), and Clip (hard and soft clipping) — designed as an all-in-one drum bus processor. The company also offers KNOCK Clipper, a standalone hard/soft clipper module, alongside sample-pack bundles tied to the DECAP catalog.

The plugins are released for macOS, Windows, and iOS in VST3, AU, AAX, and AUv3 formats, with iOS versions distributed through the App Store. The brand's marketing leans heavily on short-form social demos showing the KNOCK chain applied to drum loops, and it has become a frequently referenced tool in producer-focused YouTube and TikTok content.

Plugins That Knock has 2 products cataloged on Equipboard, including Multi-Effect Plugins and Limiter Plugins. Their gear is featured by 2 artists, with the strongest followings in Electronic, Hip Hop, and Latin. Notable users include Tainy and Eats Everything.