17NAS is a free suite of network diagnostic tools that run entirely in your browser — no signup, no install. • NAT type test — Full Cone, Restricted, Port Restricted or Symmetric NAT detection for P2P gaming and video calls • IPv6 connectivity test — reachability check with IPv4/IPv6 latency comparison • CGNAT detection — find out if your ISP puts you behind carrier-grade NAT • curl-friendly API — curl -4/-6 v4.17nas.com / v6.17nas.com, JSON output for scripts Free forever, no account needed.