Free online network tools

Why use browser-based network tools?

Every tool here runs entirely inside your browser — no server round trips, no account needed, no data sent to a third party. Whether you are diagnosing a subnet, decoding HTTP headers, or looking up a port number, all processing happens locally and results are instant.

Choosing the right tool

Use the IP/CIDR Calculator when you have CIDR notation and need the network address, broadcast, and host range. Use the Subnet Calculator when you need to split a network into equal-sized subnets. For hardware identification, the MAC Vendor Lookup decodes the OUI prefix of any MAC address. To understand command output, use the Ping Explainer or Traceroute Explainer. For web debugging, the HTTP Headers Decoder and SSL/TLS Grade Info cover the most common questions.