There is no single "duplicate project" mutation in the monday.com API. The correct approach is to use duplicate_board on the project tasks board.

See Get Project Status / Health for how to distinguish the tasks board from the portfolio board.

Duplicate the tasks board

The duplicate_board mutation is synchronous and returns the new board ID immediately:

mutation {
  duplicate_board(
    board_id: TASKS_BOARD_ID,
    duplicate_type: duplicate_board_with_pulses,
    board_name: "My Project (copy)",
    workspace_id: TARGET_WORKSPACE_ID
  ) {
    board { id name }
  }
}

duplicate_type options

Limitations

• This duplicates the tasks board only. It does not replicate portfolio linkage or companion features (e.g., Resource Planner).
• For a full project duplication including portfolio context, additional steps beyond the public API are required.