Quote from Donna Cox Baker on January 30, 2020, 3:46 am

Staying under Zotero's free 300MB limit

After ten years and more than 6,100 items in Zotero, I have only used 68% of my 300MB syncing space in Zotero's cloud. The text of your references and notes is not counted against your 300MB. It's attachments that will eat up your space, so link to your attachments externally, rather than embedding them in your data, unless you have unlimited storage with Zotero. We've talked about that before, and it's got a chapter in Zotero for Genealogy.

But if you find that your space is disappearing, anyway, try any or all of these things:

1. Empty your trash and sync. (repeat this after any other steps you take)
2. Search your database (all fields) for the term "snapshot" and get rid of the images of web sites that have been collected with Zotero Connector.
3. In your preferences--on the General tab--deselect the first two items: "Automatically take snapshots..." and "Automatically attach associated PDFs..." to prevent a further data glut.
4. Sort your research list with attachments at the top and look for any attachment icons that don't have a chain link image on them. If they do not, you have an embedded link. Move it to your hard drive and link externally. This might take a while if you've got a lot of attachments.
5. If you still believe that Zotero's storage is more depleted than it should be, try this: Go to your data storage file on your hard drive. Your Preferences--Advanced--Files and Folders will show you the "Base directory." Search that directory for the file extensions of attachments..."*.pdf", "*.jpg", and so forth. Make sure you have the attachments safely kept elsewhere with an external link from their reference item. Then delete the culprits. Remember to empty your trash and sync.

If you can afford unlimited storage, however, you are supporting the work of Zotero development. I can only encourage that.