Tools

Free tools for ops and networking

The lookups and the arithmetic you reach for while diagnosing something, with no sign-up, no account and no ads. They are the ones we use.

They run in your browser

Nothing is sent anywhere. What you paste here — a token, a header — never leaves your machine, which is what makes them the ones to use for anything sensitive.

Encode and decode

Base64, base64url, URL, HTML entities and hex, both ways.

Read and verify a JWT

Opens the three parts, checks expiry and claims, and verifies the signature if you give it a key.

They query the network

These make a public lookup from our server: a domain's DNS, its registration, its certificate. What travels is the domain you type, and nothing else.

WHOIS for a domain

Who registered it, when it expires, and which nameservers it points to.

SPF, DKIM and DMARC

The three records that decide whether your mail arrives or lands in spam, checked together.

The file stays in your browser

You give it a whole message. It is analysed here and never uploaded — what you hand over is somebody's mail. Only the domain names inside it get looked up in DNS.

Check a message: SPF, DKIM, DMARC

Upload an .eml and see whether it passes DMARC, and if it does not, exactly which of the three failed and why.

No analytics, no accounts, and nothing you look up is stored. There is no paid version of these either: they exist because they are the daily work of running something, and because they explain how we think about the products better than a brochure would.