IP CIDR Membership Checker

Check whether IPs fall inside CIDR ranges

Firewall rules, Kubernetes NetworkPolicy objects, and cloud security groups all express allowed networks as CIDR blocks. Paste a list of client IPs and candidate ranges to see which subnet claims each address. IPv4 and IPv6 are supported, and overlapping ranges are flagged so you can simplify redundant allow lists.

When to use this checker

• Validate that office egress IPs sit inside your VPN CIDR before opening an API allow list.
• Audit whether a batch of logs shares the same /24 or /32 network.
• Compare multiple overlapping RFC1918 ranges before merging them in Terraform.

Expand a single CIDR into network and broadcast details with the CIDR Calculator.