FINDING · EVALUATION

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.