Paperless-ngx is a community-supported, open-source document management system that turns physical documents into a searchable online archive. It is the official successor to the original Paperless and Paperless-ng projects and is licensed under GPL-3.0. It is self-hosted; the easiest installation method is Docker Compose, with images pulled from the GitHub container registry and an install script provided. Paperless-ngx is not a SaaS service.
No company stands behind Paperless-ngx: the project is maintained by a community of volunteers organised in teams under the paperless-ngx GitHub organisation. There is therefore no commercial parent company and no vendor-hosted service. Data stays on the server where you install the system, so a European organisation decides the storage location entirely by itself. The project documentation warns that information is stored without encryption and that the system should not run on an untrusted host. Support is provided by the community.