/api/v2/project_milestones

Creates a milestone on a project. Requires title, date, icon_id and project_id — the project must be visible to you and cannot be a template. When color_id is omitted, the milestone takes the color of its project. assignee_id must be an active member of the project. Requires the permission to manage project milestones.

Create a milestone

{
  "data": {
    "type": "project_milestones",
    "attributes": {
      "title": "Beta launch",
      "date": "2026-10-15",
      "icon_id": "icon-rocket-launch",
      "note": "Release to beta customers.",
      "assignee_id": 1002,
      "project_id": 7388870
    }
  }
}