Diagnose any domain, IP or mail setup.

Type what you're investigating. MtrXTools works out what it is and lines up the right tools.

All tools

56 tools are live. The rest are on the roadmap and arrive with the next releases.

DNS

Records, delegation and how the world resolves you.

Website

Certificates, headers and what a browser sees.

Email

Authentication, deliverability and header forensics.

Lookup

Who owns a domain, IP or network.

Connectivity

Reachability, latency and the path between.

IP & subnets

Subnet maths, IPv6 and MAC addresses, worked out in your browser.

Certificates & keys

Decode, convert and generate certificates, keys and DANE records in your browser.

Developer tools

Encoders, decoders and formatters that run in your browser.

How MtrXTools works

Paste anything

Type or paste whatever you have: a hostname, a URL, an address, an email, a CIDR block or a whole error message. MtrXTools recognises the format and suggests the checks that make sense for it, so you don't need to know which tool to open first.

Checks run from our servers

Lookups and connection tests run from servers on the public internet, the same view your visitors and mail senders get. Requests to private or internal networks are refused, and every check is read-only: nothing is changed on the systems you test.

Free, with nothing to sign up for

Every tool works without an account. Results aren't stored; your recent runs stay in your own browser, and the email header, DMARC report and subnet tools never send what you paste anywhere.

Common questions

What can I diagnose with MtrXTools?: Name resolution and DNS records, certificates and TLS settings, redirects and security headers, mail authentication (SPF, DKIM, DMARC and MTA-STS), registration data from RDAP and WHOIS, network ownership, open ports, latency and time servers. Website health combines most of them into one graded report.
Why does a site work for me but not for others?: Often one of several servers behind the same name is down, an IPv6 address is published but unreachable, or a cached answer is out of date. Website health tests every address separately, and DNS lookup can ask the authoritative nameservers directly instead of a cache.
Why is my email going to spam or bouncing?: Most delivery problems come from a missing or failing SPF, DKIM or DMARC record, or a sending server without reverse DNS. The email authentication check grades all three, and the error explainer decodes bounce codes from Gmail, Microsoft 365 and Yahoo.
Is it safe to test a server I don't own?: Yes. MtrXTools makes only standard requests, the kind browsers and mail servers make every day: DNS queries, TLS handshakes, HTTP requests and plain TCP connections, at a low rate. It never sends attack traffic, exploits or login attempts.
Can I run these checks from my own scripts?: Yes. A free JSON API covers the same tools, with an OpenAPI description, CORS and fair-use rate limits. See the developer documentation.