Lichen is built on a principle most platforms don't follow: your data lives with you, not with the service.
Where your data lives
When you write a note on Lichen, it's saved to your Personal Data Server (PDS), a server that holds your AT Protocol data. If you signed up through Bluesky, you already have one. Lichen reads and writes to it on your behalf.
What "portable" means in practice
Because your notes live on your PDS and not on Lichen's servers, other ATProto apps can read them too, if they're built to! You're not locked into Lichen's interface to access your own wiki.
If Lichen shut down tomorrow, your notes would still exist on your PDS. You'd need another ATProto app to browse them, but nothing would be lost.
Public vs. private wikis
Public wikis are readable by anyone, with no account required. The notes in them are stored on the creator's PDS and served publicly.
Private wikis are only accessible to approved members. The notes are still on your PDS, but Lichen enforces access controls so only members can read them.
Fully private wikis will be developped once the protocol permits private data.
Images and EXIF data
When you upload an image, Lichen strips its EXIF metadata before storing it. This removes information like GPS coordinates, device model, and timestamp that cameras and phones embed in image files by default.
What Lichen can see
Lichen can read and write to your PDS as part of operating the app. It can see your notes, your wiki memberships, and your bookmarks.