About

SendSignal Tools is a set of free utilities for anyone who works with email: DNS lookups, SPF, DKIM, DMARC and BIMI checks, blocklist status, header forensics, and encoding helpers. Every check explains what it finds in plain English, and every result page has a shareable URL.

Nothing you paste here is stored or logged. DNS checks query live records; paste-based tools (validators, the decoder, the header analyzer) run entirely in memory.

These tools are built and maintained by SendSignal, an email platform for developers. If you're setting up sending infrastructure and would rather not babysit DNS records yourself, that's what we do all day.

Something broken, or a tool you wish existed? Tell us. Start with the DNS lookup or the SPF checker.