Bring your existing list in, preview before writing, keep a backup.
Importing and exporting CSV
Import updates existing databases and creates new ones from one CSV. Nothing is written until you confirm the preview.
Columns
Only name and url are required. The import page has a column guide with the type of value each column expects, every allowed choice, and your current subjects, types, vendors, and proxies. Everything else is optional:
handle (the permanent link), access_level (free, card, in_library, staff), status (active, hidden, retired), short_description, long_description, alternate_names, subjects, types, tags, audiences (kids, teens, adults), languages, vendor, proxy (the proxy's name), in_library_url, ios_url, android_url, help_url, featured (yes/no), new_until, trial_ends_on, click_behavior (inherit, open, details), consortium (yes/no), internal_notes, search_hints (staff-only phrases that help search find the database, separated by semicolons), id.
Separate several subjects, types, tags, or names with semicolons: Health; Science.
How rows are matched
A row updates an existing database when its handle (current or old), id, url, or name matches one you already have, checked in that order. Otherwise it creates a new one. Rows with problems (a bad URL, an unknown access level) are listed with the reason and skipped; fix them in the file and import again.
Subjects and types you don't have yet
The preview lists every subject or type in the file that doesn't exist. For each one you can create it, map it to an existing one (for example "Medicine" → "Health & Medicine"), or skip it.
Export
Databases → Export CSV downloads everything, including internal notes and vendor, in the same column layout. Keep a copy as a backup, or edit it and import it back.