We are starting a collection of free tools for developers and site owners. They are free to use and need no account, whether or not you host anything with Cosmoner.
The first is a DNS lookup. Enter a domain and a record type, and it asks Cloudflare, Google and Quad9 and the domain's own nameserver at the same time, then shows their answers side by side. When the answers differ, a recent change is still working its way through the caches; once they agree, it has arrived. That makes it a quick way to follow a migration, check that a verification record is live, or see why email still goes to an old provider.
It covers A, AAAA, CNAME, MX, TXT, NS, SOA, CAA and SRV records, plus reverse DNS for an IP address. Each type has its own page explaining what the record does and what to look for in the answer, such as the MX lookup or the reverse DNS lookup. Every result has a link you can share, so you can send someone exactly what you are seeing.
The lookup also points out what could be improved in the answer: a domain with no mail servers, two SPF records, a DMARC policy that only monitors, a single nameserver, an address with no reverse DNS, and more. Each suggestion says what it saw and what to change, and links to the next record worth checking. If something looks wrong, Report a problem on the page sends it straight to us, with what you looked up attached.
More tools will follow.