The Ahmia search engine provided the most onion addresses (18,069 in a single day,
ranging 18,000–22,000 week-to-week), outperforming five other sources combined
(36,028 total across six engines). However, Ahmia's intentional exclusion blacklist
contains 46,000+ hashed addresses, and crawling onion services for 20 days yielded
48,745 unique v3 addresses, 11,809 of which were on Ahmia's blacklist — meaning
any index-based collection systematically misses a significant share of the onion
ecosystem by design.
From 2025-h-ller-evaluating — Evaluating Onion Address Collection Methods
· §4.1, §4.3
· 2025
· Free and Open Communications on the Internet
Implications
Onion addresses maintained outside search-engine indices (e.g., private bridges, restricted distribution circumvention services) are not discoverable by adversaries using only public collection methods; operators can use non-indexed .onion addresses as a modest privacy layer for distribution endpoints.