Combining six onion search engines/repositories plus clearnet search engines,
Tor2web-style DNS leakage, and 20 days of self-run crawling (2.9 million pages),
the authors assembled 482,614 unique v3 onion addresses — the largest known
collection. Verifying against HSDir blinded public keys showed the collected
addresses accounted for 25% of observed blinded keys but were responsible for
66% of all successful service descriptor downloads, confirming a heavy-tailed
usage distribution.
From 2025-h-ller-evaluating — Evaluating Onion Address Collection Methods
· §4, §5
· 2025
· Free and Open Communications on the Internet
Implications
A small fraction of onion addresses accounts for most descriptor downloads; privacy-sensitive circumvention onion services (Cwtch, Briar) that avoid public indexing will be systematically underrepresented in any collection-based study — measurement results about 'Tor onion usage' are skewed toward popular/ commercial services, not dissident use cases.