Filecoin chain snapshots and the proof-parameter set archived on PDP storage providers, with proofs shown live and a node you can rehydrate on demand.
A Python archiver stores Forest calibnet snapshots and the Filecoin proof parameters on storage providers through filecoin-pin, split into parts with a manifest. The site shows the on-chain proof status for every piece, streams parts back out, and can rehydrate a Forest node from what is stored.
The third tab loads a blockchain dataset straight from Filecoin into DuckDB in the browser and runs SQL over it, which is the part people tend to remember.