Since 2008, the RoughRider series of compressors has been a mainstay of electronic and hip-hop music. With over half a million downloads, this workhorse is easily one of the most used compressors in the music business. With version 3, Audiodamage has made it even more useful. They have added an external sidechain input, sidechain HPF, a "full bandwidth" switch that turns off the internal warming filters, input and output level controls, and an all-new GUI with full input, output, and gain reduction metering and graphs.
The best news? RoughRider3 is still free! Head to the Audio Damage site, and you'll find it on the Free Downloads tab. For macOS AAX, AU, VST, and VST3, Windows AAX, VST, and VST3, Linux VST, and iOS standalone and AUv3.