Paperless-ngx deserves more attention.
Scan a physical document → OCR extracts all text → ML suggests tags and correspondents → full-text search across your entire document library.
Pair it with a $50 document scanner and your filing cabinet becomes a searchable database. Every receipt, letter, tax form — indexed and findable in seconds.
One Docker Compose stack. Redis + PostgreSQL + Paperless + Gotenberg (document conversion).