As far as I understand, user access levels are determined on a per-file basis, so you can only know a user’s permissions level in relation to a file that they have requested the information of.

You can check the “role” property on the json of a successful response to an endpoint that requests a Figma file’s information.

For example, if an authenticated user makes a request to https://api.figma.com/v1/files/:file_key, a successful response might look something like this:

{

  document: ...

  components: ...

  componentSets: ...

  schemaVersion: ...

  styles: ...

  name: ...

  lastModified: ...

  thumbnailUrl: ...

  version: ...

  role: 'editor' <-- this property is what you're looking for

  editorType: ...

  linkAccess: ...

}

The role property can be one of “viewer”, “owner”, or “editor”. If you get a response with a 404 status you can assume the authenticated user has no associated permissions with the file they requested (or the file does not exist).