Where are the ReSharper cache files kept in Rider?

Rider has to store both ReSharper and IntelliJ settings and cache files.

Windows

On Windows, the ReSharper host cache files are kept in the %LOCALAPPDATA%\JetBrains\Rider{version}\resharper-host\local\Transient\ReSharperHost\v{version}  folder.

The global settings are in %APPDATA%\Roaming\JetBrains\RiderXXXX.X\resharper-host. The IntelliJ global settings are stored in %USERPROFILE%\AppData\Roaming\JetBrains\RiderXXXX.X, and the per-project settings in the solution local .idea folder.

OSX and Linux

On OSX and Linux, Rider stores the ReSharper host persistent settings in ~/.config/JetBrains/, and ReSharper solution caches in ~/.local/share/JetBrains. The IntelliJ global settings are stored in ~/Library/Application Support/RiderXXXX.X, and per-project settings in the solution local .idea folder.

HINT: {version} in a path depends on the ReSharper version which is used in current Rider build.