I created a set of rules to manage the size of the .SyncTrash folders. It really is a bit of a hack, but seems to work (please please test on dummy folder yourself before you trust this). It uses Hazel and thus is a Mac-only solution, but could be reproduced with a script on other platforms. Get read-only access using R635ATSVHLPUENHGKIJBW7ZNOF42AGEFK I'll try to update the files with improvements as time permits. Contents: Hazel (http://www.noodlesoft.com) rules to automatically delete files contained in ./.SyncTrash folder created by BTSync after a user-specified period. This is a temporary, Mac-specific hack while we wait for a built-in solution; currently, deleted files would otherwise stay on disk forever or until manually deleted. This can be done using cron jobs, etc. Hazel is just easier. What these rules do: - watch BT SyncTrash folders - compress each file (zip) one day after it was moved to .SyncTrash - delete zipped files after 30 days - delete empty folders - apply all the above recursively to nested folders How to set up these rules in Hazel: - show hidden files & folders in Finder (made easier if you use TotalFinder or PathFinder) - add every .SyncTrash/ folder you have, i.e. one per root folder synced by BTSync - import the hazel rules. - feel free to tweak dates, etc. Hope this helps.