The short answer
Usually, after a check. Might hold something you care about. Look inside before removing it.
What is it?
Jan, an open-source app for running language models locally, keeps its data folder in ~/Library/Application Support/Jan/data. It contains downloaded models, your conversation threads, assistants and settings. Models make up most of the size, typically a few GB each.
Jan's downloaded models and your conversations. Remove models from Jan; conversations are not recoverable.
What happens if you delete it?
Models can be downloaded again from Jan. Conversations and assistant settings are not recoverable once deleted.
How to remove it properly
In Jan, open Settings › Model Providers and delete the models you no longer use. Do not delete the whole data folder unless you want to lose your chats.
From the app itself: Jan > Settings > Model Providers: delete models you don't use.
Before you delete it
Your conversations live here; export any you want to keep before resetting Jan.
How MoreRoom helps
MoreRoom recognises this item and labels it “Review first”: it shows what’s inside, its size and last use, so you can decide. Nothing is removed without your say, and everything goes to the Trash first, with Undo.
Frequently asked questions
Can I delete Jan’s data folder on Mac?
Usually, after a check. Might hold something you care about. Look inside before removing it. Models can be downloaded again from Jan. Conversations and assistant settings are not recoverable once deleted.
Will Jan models and data come back after I delete it?
No. Models can be downloaded again from Jan. Conversations and assistant settings are not recoverable once deleted.
How do I remove Jan models and data properly?
In Jan, open Settings › Model Providers and delete the models you no longer use. Do not delete the whole data folder unless you want to lose your chats.