Runs on our serverDNS and email health checkMX, SPF, DKIM, DMARC and blocklists for a domain, with plain-English verdicts.Runs in your browserAdmin utility beltRegex tester, cron explainer, Base64, JWT decoder, hashes, JSON, passwords and UUIDs. All in your browser.Runs on our serverSSL/TLS certificate checkerExpiry, issuer, names and chain for a site's certificate, and the TLS version it negotiates.Runs in your browserSubnet calculatorIPv4 and IPv6 CIDR: network, range, mask and host count, plus a subnetting practice mode.ReferenceError code lookupWhat an error code means and how to fix it: Exchange, Entra sign-in, Windows Update, printing and more.Runs on our serverWhat's my IP?Your public IP address, and who owns any public address (network, ASN, country).Runs on our serverEnd-of-life trackerWhen Windows, Windows Server, Office, SQL Server, Exchange, Ubuntu and more stop getting updates.
Tools that run in your browser never send what you type anywhere. Tools that run on our server see only what you ask them to look up, and none of it is stored: results are cached for a few minutes so repeat lookups are quick.