IP address checker
Not every IP that reaches your application is a real client address. Some can never be one. This tells you which kind you are looking at, and what it means if you found it in a log.
Free, no signup, no daily limit. We do not store what you check here.
When a private IP is a bug, not a fact
If a private address such as 10.0.0.1 or 192.168.1.1 shows up as a user IP in your logs, the address is not the problem - your reverse proxy configuration is. Something is reading a forwarded-for header that either was not set or was set by the client. Any rate limiting or fraud scoring keyed on that value is scoring your own load balancer.
Carrier-grade NAT changes what an IP means
The 100.64.0.0/10 range is shared between subscribers by mobile carriers and some ISPs. Thousands of unrelated people can appear behind one address. Blocking or rate-limiting it as though it were one user blocks a whole city, which is why it deserves separate treatment rather than being lumped in with public addresses.
Questions
Does this show me a location?
No. This tool answers what kind of address it is, using offline range tables. Geolocation needs a licensed database, which the paid API uses.
Is IPv6 supported?
Yes, for format validation. Range classification is most detailed for IPv4.
Related tools
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.
Carrier-grade NAT (CGNAT) checker
Check whether an IP sits in the 100.64.0.0/10 carrier-grade NAT range shared between mobile subscribers. Free.
MX record lookup
Look up the MX records for any domain and see who handles its mail. Free, live DNS query, no signup.
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.