List of free document-management-system stuff for developerππ½
If you're looking for all programming tools around document-management-system (not just free). Check this page List of document-management-system Programming Tools

FormKiQ
Open Source Headless Document Management System (DMS) that runs in your Amazon Web Services (AWS) Cloud. Can be used for document workflows, records management, and other document storage and processing needs, using an extendable Document API.
Tag: document-management-system, serverless, aws
FormKiQ Core installs into AWS with no limits