Explained
An IP pool is the underlying inventory of IP addresses a proxy gateway can route customer traffic through. When you connect to a rotating proxy and the gateway picks an exit IP, it picks from this pool. Pool quality is the single biggest variable that determines whether your scraping or verification workload succeeds.
Three dimensions matter when evaluating an IP pool: size (raw count of available IPs), diversity (number of distinct subnets and ASNs covered), and geo coverage (how many countries / cities / ISPs are represented). A pool with 10M IPs spread across 1000 subnets is usually more effective than a pool with 100M IPs concentrated in 50 subnets, because anti-bot systems track IPs at the subnet and ASN level, not just the individual IP.
Freshness also matters. Residential pools that grow through opt-in SDK partnerships continuously cycle IPs in and out as users join and leave the network. A pool that's been stagnant for months will have more IPs already flagged on common targets than a pool that refreshes weekly.
How It Works
Residential proxy providers maintain their pool by partnering with applications and SDKs that users opt into in exchange for free or premium features. When a user is online and the SDK is active, their device contributes its IP to the proxy pool for the duration. The provider's gateway treats the device as an available exit endpoint, routes a small amount of customer traffic through it, and removes it from the pool when the user goes offline.
Large providers maintain millions of devices in the active pool at any given moment, with new devices coming in and out continuously. The gateway selects exit IPs based on geo filters, IP health, and load balancing, presenting customers with a single endpoint that abstracts away all the underlying churn.