refnet is a unified, knowledge-graph reference for the file formats, protocols and identifiers developers touch every day.
Instead of nine separate lookup tools, refnet connects file extensions to their MIME types, HTTP headers, programming languages, DNS records, TLDs and network ports — so one query naturally leads to the next.
All reference data is derived from public open-source registries: mime-db, GitHub Linguist, IANA and know-your-http-well. We fetch the raw data, clean and structure it locally, cross-link the entities, and keep the site updated as those sources change.
refnet is free to use. Advertising on the site is served by Google AdSense.
Questions, corrections or data requests? We're happy to help — email us at: