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+# Shared Cache
+
+Archipelago maintains a shared folder of information that can be persisted for a machine and reused across Libraries.
+It can be found at the User Cache Directory for appname `Archipelago` in the `Cache` subfolder
+(ex. `%LOCALAPPDATA%/Archipelago/Cache`).
+
+## Common Cache
+
+The Common Cache `common.json` can be used to store any generic data that is expected to be shared across programs
+for the same User.
+
+* `uuid`: A UUID identifier used to identify clients as from the same user/machine, to be sent in the Connect packet
+
+## Data Package Cache
+
+The `datapackage` folder in the shared cache folder is used to store datapackages by game and checksum to be reused
+in order to save network traffic. The expected structure is `datapackage/Game Name/checksum_value.json` with the
+contents of each json file being the no-whitespace datapackage contents.