Contributing a Tor Bridge to the Tor Project: 2026 Guide

Tor network contributions fall into several categories. Bridge (unlisted relay): helps censored users by providing a non-publicly-listed entry point. Bridge addresses are distributed via BridgeDB to users in censored countries. Bridges only need to accept incoming Tor connections, not carry exit traffic. Low operational complexity. Middle relay (non-exit): listed publicly, carries Tor traffic between guard and exit. Contributes capacity but does not face abuse complaints (does not exit to the internet). Guard relay: listed publicly, serves as stable entry point for Tor clients. Requires high uptime and bandwidth. Exit relay: carries Tor traffic from the network to the public internet. Most impactful for network capacity. Faces abuse complaints. If you cannot run an exit relay (due to hosting restrictions or abuse handling concerns), a bridge is the most impactful contribution you can make for censored users.

After your bridge is running and stable (allow 48-72 hours for Tor's directory system to learn about it), register with the Tor Project's bridge database. Registration: the bridge fingerprint (displayed in Tor logs or via `tor --fingerprint`) is submitted via the bridge operator application at bridges.torproject.org/submit. Include: transport types supported (obfs4, WebTunnel, Snowflake), contact information (optional, for urgent security notices), and any distribution restrictions (you can request that your bridge only be distributed to users from specific countries). After registration, your bridge begins appearing in BridgeDB queries. Tor Metrics will show bridge statistics (usage, countries served) after a week of registration.

Tor's bridge directory does not use the same flag system as the public relay directory, but bridges have quality characteristics that affect their distribution priority. Stability: bridges that have been running consistently for 30+ days receive preference in distribution. Uptime: bridges with >95% uptime are preferred. Bandwidth: bridges offering more bandwidth serve more users. The bridge reachability test (run by BridgeDB periodically) verifies your bridge is online and the transport is responsive. If your bridge fails reachability tests repeatedly, it is removed from distribution. Monitor your bridge's status via Tor Metrics (search by fingerprint) to verify it is active in the database.

After your bridge is registered and in use, Tor Metrics provides usage graphs. Metrics available: bandwidth usage over time, estimated number of unique users, and countries from which users are connecting. Interpreting the stats: if your bridge is an obfs4 bridge and you see connections primarily from Iran or Russia, your bridge is reaching its intended audience. Snowflake bridges show connections distributed globally based on proxy availability. Bandwidth graphs show actual usage - a bridge that shows zero usage may not be reachable (check reachability in bridge database) or may not have been distributed to users yet (takes 1-2 weeks for new bridges to enter regular distribution).

Long-term bridge operation requires: keeping Tor updated (new Tor releases include security fixes and performance improvements; the Tor Project's apt repository provides automatic updates), monitoring server health (disk space, RAM, network), and responding to the Tor Project's contact if you provide contact information (rare, but they may notify of critical issues). Bridge retirement: if you need to take your bridge offline permanently, it will be removed from BridgeDB after failing reachability tests. No manual deregistration is required, but notifying bridges@torproject.org is courteous and allows faster removal from distribution to prevent users from receiving non-functional bridge addresses. Appreciation: the Tor Project publishes total bridge counts and credits the operator community. Your contribution, while anonymous in operation, is part of a global network helping millions of users bypass censorship.