Audio Damage, Inc. just released RoughRider3. This is a follow-up to their popular Rough Rider compressor, and is free on all platforms! There's even an experimental Linux version available! The iOS version includes External Sidechain input when used in AUM!
RoughRider3 App Store Description:With almost a quarter million downloads, the free Rough Rider compressor from Audio Damage is one of the most popular plugin effects on the planet.
RoughRider3 expands on the original RoughRider and RoughRider2. New features:
• External Sidechain Input in hosts that support it. (Currently only AUM)
• Sidechain HPF control (works on both normal operation and external sidechain, for removing the low end from the compression algorithm.)
• Input and Output level controls, for easier level tuning.
• FULL BANDWIDTH control removes the warming features and high end attenuation from the original RoughRider, for a cleaner sound.
All this in addition to the original RoughRider compression you know and love. RoughRider3 installs both an AUv3 and a standalone with Inter-App Audio.