Network Diagnostics
All-in-one DNS lookup, IP geolocation, WHOIS, SSL, HTTP headers, and subnet calculator. Free, no sign-up.
About These Tools
Built for developers, sysadmins, and IT professionals who need quick network diagnostics. Most lookups run from our servers, so results reflect the actual resolved values from authoritative DNS and RDAP registries — not your browser's cached data.
- DNS Lookup uses DNS-over-HTTPS (Cloudflare + Google fallback) for privacy.
- IP Lookup uses ip-api.com's free geo database (city-level accuracy, ASN included).
- WHOIS uses modern RDAP protocol (structured JSON, faster than legacy WHOIS).
- SSL Checker performs a real TLS handshake to inspect the live certificate chain.
- HTTP Headers flags common security headers (HSTS, CSP, X-Frame-Options, etc.).
- Subnet Calculator runs entirely in your browser — no data leaves.
What this tool does
Choose among DNS, IP, domain registration, TLS, header and subnet checks.
How to use it
Select the check that matches your question. Use the dedicated tool link when sharing a workflow.
Worked example
For a DNS problem, choose DNS Lookup and inspect A records; for 192.168.1.10/24, choose Subnet Calculator to get network 192.168.1.0.
Limitations and checks
The hub shares implementations with the dedicated pages. Network failures can reflect this server’s connectivity rather than a global outage.
How your data is processed
Online lookups contact server endpoints and relevant providers. Subnet calculation alone is local.
Privacy and storage details · Report an incorrect result · Browse tools