I've built Sneak Link to solve a common selfhosting problem: securely sharing content from internal services like NextCloud, Immich, or Paperless without exposing the entire service to the internet.
Sneak Link works by using the share link itself as a kind of "knock", similar to old school port knocking. When someone accesses the link, Sneak Link verifies it with the backend service (e.g. NextCloud) to confirm that it's valid and public. If it checks out, SneakLink sets a signed cookie that grants temporary access to the service.
It's designed for self-hosters running these services on internal networks who still want to share files or photos with friends and family. Right now, it supports NextCloud, Paperless-ngx, Immich, Seafile and Photoprism. It has a simple dashboard: https://github.com/felixandersen/sneak-link?tab=readme-ov-fi... and a Prometheus metrics endpoint.
The project is open source. I have aimed at making it lightweight, with minimal dependencies. The architecture allows new services to be added. I'd love feedback from others running self-hosted setups or ideas for new integrations!