Network & Web

CIDR Calculator

Calculate network address, broadcast, host range, usable IPs and subnet mask for any IPv4 CIDR block.

Browser Info Detector

See what your browser reports: user agent, engine, version, OS, device type, screen resolution, timezone, language and public IP.

HTTP/2 and HTTP/3 Checker

Analyze pasted response headers locally to identify the observed HTTP version and any HTTP/3 Alt-Svc advertisement.

API Endpoint Checker

Test a CORS-enabled HTTP or HTTPS endpoint from your browser. Inspect its final status, exposed headers, response time and a bounded body preview.

Email Header Analyzer

Analyze raw email headers privately in your browser. Review Received hops, timing, SPF, DKIM, DMARC and ARC metadata without uploading a message.

Speed Test

Run a fast, free, browser-based internet speed test. Measure your download speed in Mbps plus round-trip latency and jitter, and see whether your connection is ready for 4K streaming, gaming and video calls, no app, no signup.

Reverse DNS Lookup

Look up the PTR record for an IPv4 or IPv6 address. Useful for mail-server debugging, log analysis and spam-filter investigations.

What Is My IP

See the IP address this server received for your request, its IPv4 or IPv6 family, and an approximate country when local GeoIP data is available.

IP Address Lookup

Look up any public IPv4 or IPv6 address for approximate country, region, city, coordinates, ISP, ASN, organization and timezone.

WHOIS Lookup

Look up public WHOIS registration data for a domain: registrar, nameservers, status codes and expiry dates.

DNS Lookup

Query the A, AAAA, MX, TXT, NS, CNAME and SOA records of any domain without opening a terminal.