Free tools to check domains, email and servers. Each one runs in your browser, needs no sign-up and explains the result in plain English, with the matching terminal command so you can repeat the check yourself.
DNSDNS LookupEvery DNS record of a domain, compared across Cloudflare, Google and AliDNS.Open tool EmailEmail Deliverability CheckFind out why mail goes to spam: SPF include tree, DKIM and DMARC in plain English.Open tool SecurityNewSSL Certificate CheckerExpiry date, certificate chain, covered names and TLS version of any HTTPS site.Open tool ChecklistDebian Server Security ChecklistEvery step to lock down a Debian 13 or 12 server, with the exact commands.Open tool
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