For one board, open the board menu then Print, Export, and Share then Export; JSON is open to all board members and CSV requires a board in a Premium Workspace. For every board at once, go to Workspace Settings then Export, then choose CSV or JSON, which only a Workspace admin on Premium can create and download. Select Include raw attachments to get attachments in their original formats inside a ZIP, and note the JSON holds only the 1000 most recent actions on a board while CSV leaves out comments and cards closed off the board.
What it holds
Boards, lists, cards, card descriptions, comments, attachments and board activity.
Find the size
Trello's export page shows no storage figure or card count. Quote the card row count of the CSV and note the 1000 action cap on the JSON.
What to enter on the form
Trello in records, and the year your company started using it. Seller form