Parses an uploaded Trello, Jira, Asana, CSV or craaft export and returns what POST /imports would create. Nothing is written. The preview and the import run the same code, so the counts match.

multipart/form-data, file up to 5 MB. Limits per import: 2,000 cards, 200 columns, 500 checklist items on any one card, 20,000 checklist items and 20,000 comments in all, 200 CSV headers. source is detected from the file when omitted. For CSV sources, mapping replaces the server's suggested mapping: send every field you want imported. The response then carries a csv block with the headers, the mapping in use and the first sample rows. When no title column can be guessed and no mapping is sent, the preview still answers 200 with the csv block and an empty summary named after the file, so the client can map the title and preview again.

Matched assignees who aren't you or a workspace owner or admin are listed in access: the import adds them to the new private board as contributors.

{
  "warnings": [
    {
      "code": "closed_lists_skipped"
    }
  ]
}