Dernium Webtools

Free configuration tools for IT operators. Generate and validate security.txt, DMARC, SPF, CAA, MTA-STS, BIMI, CSP headers, robots.txt, TLS cipher lists, TLS cert chains, DANE/TLSA, MX health, JWKS and more. Generators run locally in your browser; validators with a DNS or STARTTLS path go through our server with no logging. No sign-up, no cookies.

No sign-up No cookies Browser-local where possible Standard reference per output

Web

Email

TLS and certificates

Other

How we handle your input

Configuration tools often touch sensitive data: domains, mail servers, internal IPs, sometimes JSON web tokens. Wherever possible, every tool on this page builds its output entirely inside your browser. Cut the network and keep working - or read the source to confirm.

Some tools must query foreign domains to check something that the browser cannot do itself (CORS, or protocols like DNS / SMTP-STARTTLS). Those tools run on our server. We do not log the queried domain or the result and do not persist anything in a database; a hashed rate-limit table per IP subnet is used but discarded periodically.

Generators stay fully browser-local. Several validators also offer a local paste mode (JWKS, TLS cert chain) that never sends anything to our server - every page surfaces a banner at the top showing which path is currently active.