# Update all user attributes Replaces a user's attributes. This will replace any existing attributes for the user with the attributes in the payload. To leave existing attributes in place, use PATCH. Endpoint: PUT /v3/users/{user_id}/attributes Version: 2026-01-08 Security: ZephrHmacHttp ## Path parameters: - `user_id` (string, required) Unique User identifier ## Request fields (application/json): - `first_name` (string) Example: "Joe" - `surname` (string) Example: "Blow" ## Response 200 fields ## Response 400 fields ## Response 404 fields