Network & IP Tools
Free network utilities for developers and sysadmins: subnet and CIDR calculations, IP geolocation, DNS lookups, HTTP inspection, port reference, and IPv6 tools. Client-side where possible.
Subnet Calculator
Calculate subnet masks, ranges & hosts
CIDR Calculator
Network, broadcast & host range from CIDR
CIDR Overlap Calculator
Check if CIDR blocks overlap
IP Range Calculator
Calculate IP ranges & CIDR blocks
IP Lookup
Find IP geolocation, ISP & network info
DNS Lookup
Query DNS records via Cloudflare DoH
User Agent Parser
Detect browser, OS & device from UA strings
HTTP Header Viewer
Inspect HTTP response headers for any URL
HTTP Status Lookup
Look up HTTP status codes and meanings
Port Checker
Common port reference & service lookup
IPv6 Tool
IPv6 address tools and utilities