Eiosis is a French audio plugin developer founded by Fabrice Gabriel, a computer-science engineer and mix engineer who later became co-founder and lead algorithm designer at Slate Digital. Launched in the mid-2000s, the company focuses on mixing and mastering tools, and its catalog is now distributed under the Slate Digital umbrella.

Eiosis is best known for the AirEQ Premium, a nine-band equalizer with distinctive Air, Earth, Water, Fire, and Strength shaping controls aimed at mastering and mix-bus work. The lineup also includes the E²Deesser, a de-esser plugin, and the Air and Earth modules for Slate Digital's Virtual Mix Rack. Plugins ship in VST, VST3, AU, and AAX formats for macOS and Windows.

The brand has found an audience among mixing and mastering engineers who favor musical, ear-centric processing over surgical or modeled workflows, and its tools are frequently cited in pro audio reviews and forums for offering broad tonal control with relatively few parameters.

Eiosis has 3 products cataloged on Equipboard, including EQ Plugins and De-Esser Plugins. Their gear is featured by 12 artists, with the strongest followings in Pop, Hip Hop, and K-pop. Notable users include Underworld, Suga (Agust D), and J. Cole.