All tools
Free to use, no login required. Each tool is also a JSON API. The blacklist sweep, SSL grader and monitoring suite are next on the roadmap.
IP
What's My IP
Your public IPv4/IPv6 and the request headers that matter — no third parties involved.
CIDR Calculator
Network, broadcast, mask, wildcard, host range and counts for any IPv4/IPv6 CIDR.
IP Range → CIDR
Convert an inclusive IP range into the minimal set of CIDR blocks.
Network
Ping
ICMP round-trip time to a host, measured from our IPv4 and IPv6 probes.
Port Check
Test whether a TCP port is open and how fast it connects — over IPv4 and IPv6.
HTTP Check
Fetch a URL from our probes and report status, redirects and response time per stack.
SMTP Banner
Connect to a mail server and read its SMTP banner — mostly an IPv4 story.
Diagnostics
Speed Test
Download, upload and latency to our IPv4 and IPv6 servers — no Flash, no ads.
WebSocket Test
Check whether your network allows WebSocket connections — some proxies and firewalls block them.
Sound Test
Play test tones to check your speakers and headphones — left, right and both channels.
Webcam Test
Preview your camera and confirm it works — nothing ever leaves your browser.
DNS
Blacklist Check
Sweep an IP across dozens of DNS blacklists (RBLs) at once — see exactly which ones list it.
MX Lookup
List a domain’s mail exchangers in preference order.
SPF Check
Parse SPF and count DNS lookups against the RFC 7208 limit of 10 — the one that catches everyone.
DMARC Check
Resolve and validate the DMARC policy at _dmarc.<domain>.
DKIM Lookup
Fetch a DKIM public key by selector and flag weak keys.