For software that opens dozens of threads at once, free public lists go dead quickly. An IPv4 pool with rotation works where public addresses get blocked. For tasks like these, users pick private addresses with spare threads. Pool and plans: https://telegra.ph/HTTP-Proxy-Service-11-10 Addresses come from all over the world and traffic is unlimited. Traffic is not billed by the gigabyte. For Proxies for SEO tools GSA checker setup stays simple.