Sonnox is a British audio software company based in Finstock, Oxfordshire, with roots stretching back to 1988. A team of engineers who had worked together at Solid State Logic left to form Oxford Digital, where they designed the OXF-R3 digital mixing console — a flagship product released commercially by Sony in the mid-1990s with a base price of $1 million. The console became widely regarded as the first truly "musical"-sounding digital console and was installed in major studios worldwide. As the industry shifted toward computer-based production, the team ported the console's DSP algorithms into plugin format under the Sony Oxford banner. In 2007, Rod Densham led a management buyout of the software division, forming the independent company Sonnox.

Sonnox's product line centers on the Oxford range of plugins, which includes the Oxford EQ, Oxford Dynamics, Oxford Reverb, Oxford Limiter, Oxford SuprEsser, Oxford Envolution, Oxford Dynamic EQ, and Oxford Drum Gate 2. Their most celebrated plugin is the Oxford Inflator, a unique loudness-enhancement tool that adds perceived volume, warmth, and presence without traditional compression artifacts — widely considered a "secret weapon" among mixing and mastering engineers. The company also offers a Toolbox range of more accessible creative tools, including VoxDoubler for vocal doubling effects, Claro for guided EQ workflows, and Voca for vocal processing.

Sonnox plugins are used by Grammy-winning engineers and producers including Tony Maserati (Beyoncé, Santana, Lady Gaga), Kevin Killen (U2, David Bowie, Peter Gabriel), and Simon Climie (Eric Clapton, Stevie Wonder). The company is part of the Focusrite Group.

Sonnox has 45 products cataloged on Equipboard, including FX Bundle Plugins, EQ Plugins, and Limiter Plugins. Their gear is featured by 66 artists, with the strongest followings in Electronic, Pop, and Rock. Notable users include Andy Gray, Omar Hakim, and Rik Simpson. Most Sonnox products sit firmly in the high-end, boutique range.