Explained
A sticky session is the opposite of per-request IP rotation: rather than picking a new exit IP for every request, the proxy gateway pins one IP to your traffic for the duration of a session. The session is typically scoped by a session ID you pass in the proxy username (e.g. `customer-USER-session-abc123`) and lasts until the gateway's stickiness window expires (commonly 1, 5, 10, or 30 minutes).
Sticky sessions are essential for any workflow where the destination site binds state to the source IP. Login pages, multi-page checkout flows, IP-bound CSRF tokens, paginated search results, and most account-management tasks all require the same IP across multiple requests. If you used per-request rotation, the second request would land on a different IP and the destination would treat it as a new, unauthenticated visitor.
Most residential proxies proxy providers expose both modes through the same gateway. You opt into stickiness on demand by including a session ID in the proxy auth, and you opt out by removing it.
How It Works
When you connect to a rotating proxy gateway with a session ID in your auth credentials, the gateway hashes the session ID and binds it to a specific exit IP from the pool. All subsequent requests using the same session ID are routed through that IP until the stickiness window expires or the IP becomes unhealthy.
When you change the session ID (or stop sending one), the gateway picks a new IP. This gives you per-workflow stickiness without losing the diversity benefit of the pool — different workflows running in parallel each get their own pinned IP, while still drawing from the same large rotating pool.