We have lots of free Unity goodies available on GitHub so be sure to give them a look!

Read the release notes before updating any plugin! Important information may be present.
In the coming months, all Unity plugin code is being moved into the Plugins/Prime31/PLUGIN_NAME folder. Be sure to mind the release notes and delete the Plugins/PLUGIN_NAME folder when updating to avoid duplicate files. You can use the Plugin Manager (Tools -> prime[31] -> Plugin Manager menu item) to quickly and easily uninstall a plugin before updating.
Android plugins are undergoing some massive changes. They will all be aar bundles going forward. Additionaly, any plugins that require Google SDKs or Android support/compat libraries will have the dependencies managed by Google's Jar Resolver. This should cut down massively on download sizes and also chop the Java object count significantly.