Files API Now Supports Project-Level Custom Attribute Definitions and Large Drop-down Lists

Files API Now Supports Project-Level Custom Attribute Definitions and Large Drop-down Lists eason.kangEDLV4 5 Aug 2026 Eason Kang Share Disclosure: parts of this post were produced with the assistance of AI tools, then reviewed and edited by the author. Custom attributes on files in Autodesk Forma projects just got two updates: a new GET custom-attribute-definitions endpoint that retrieves all custom attribute definitions for a project, and support for large drop-down list custom attributes with up to 2,000 values. With this update, you can now: Retrieve all custom attribute definitions for a