Blue Cat's PatchWork is a macOS application designed to host multiple AU and VST plugins while allowing users to create parallel chain effects. The app can support up to 64 different plugins at the same time, thanks to a feature that lets users create up to 8 parallel chains.
When you start the application, you may find the interface to be overcrowded and confusing. This is primarily because of the multiple buttons, poorly placed and with a bad text formatting. Also, the toolbar menu icons look too small and feel clunky. Yet, if you're not pleased with the default theme, you can choose another one from the Preset skin tab.
As for its features, Blue Cat's PatchWork comes with 30 effects, such as filters, delays, modulation effects, waveshaper, gate, bit crusher and more. It also has a function, called Parameters Mapping, that maps sub plugins parameters in order to automate them or use a control surface. Moreover, it supports VST Shell plugins and comes with Global Dry/Wet control. Last but not least, it can host up to 8 virtual instruments in parallel, while mixing them with the plugin.
In conclusion, Blue Cat's PatchWork is a reliable tool for hosting Audio Unit or VST plugins simultaneously, and it comes with many cool features, but the price seems a bit high. Still, feel free to give it a try.