Domain & Web Tools

Inspect DNS records, certificates, redirects, headers and how a page presents itself.

DNS LookupEvery record a domain publishes, with what they imply about its mail and certificates.Secure lookup
Security Headers CheckerWhat each header does, what yours actually says, and the line to add. No letter grade.Secure lookup
SSL Certificate CheckerRead the certificate a site actually presents — including the broken ones your browser refuses to show you.Secure lookup

What these tools have in common

Everything here asks a question about somebody else's domain: which records it publishes, which certificate it presents, where a URL eventually lands, what headers come back.

That means these are the tools on the site that make outbound requests, and they are the ones we have been most careful with. Each one validates the target, refuses private and internal addresses, re-checks after every redirect, caps the response size and gives up quickly. The point is to be a useful diagnostic, not a general-purpose fetcher pointed at whatever anyone types.

Results are cached briefly — that keeps the tools fast and stops them being useful as an amplifier.