Retrieve a list of all supported field names available on your lead records by using the Describe Lead endpoint.
Note: The REST API and SOAP API use different naming conventions for lead fields.
Alternatively, you can get the field names by following these steps:
1. Navigate to Admin > Field Management menu.
2. Click on the Export Field Names menu item, and you’ll be prompted to save a file named Fields.xls.
3. The columns named “REST API Name” and “SOAP API Name” in this spreadsheet lists all field names.