Carrier-grade NAT (CGNAT) checker
Addresses in 100.64.0.0/10 are shared between many subscribers on a mobile or ISP network. Treating one as a single user is how you end up blocking an entire city.
Free, no signup, no daily limit. We do not store what you check here.
Why CGNAT exists
IPv4 addresses ran out. Carriers put thousands of subscribers behind a shared pool defined by RFC 6598, using the 100.64.0.0/10 block. It is neither private in the RFC 1918 sense nor publicly routable, and plenty of tools classify it as one or the other.
What it breaks
Per-IP rate limiting, IP-based fraud scoring, geo-blocking and "one account per IP" rules all assume an address maps to roughly one household. Under CGNAT that assumption is simply false, and enforcing it punishes mobile users for being on a mobile network.
Questions
Is CGNAT the same as a private IP?
No. RFC 1918 addresses are for internal networks and never appear on the public internet. CGNAT addresses sit between the subscriber and the internet on a carrier network.
How should I handle it?
Raise your per-IP thresholds substantially for this range, and lean on device or account signals instead.
Related tools
IP address checker
Check whether an IP address is public, private, reserved or carrier-grade NAT. Free, no signup, IPv4 and IPv6.
Datacenter IP checker
Check whether an IP belongs to a hosting provider such as AWS, Google Cloud or Hetzner rather than a home connection. Free.
When you need more than a free tool
This page answers what can be determined offline and from public DNS. The API adds live carrier and mailbox verification, a calibrated confidence score, and the full evidence trail behind every verdict.
Credits never expire. Inconclusive verdicts are never billed. Cancel in one call. See pricing or read the docs.