Free DKIM Checker
Enter a domain and selector to see the DKIM public key published in DNS, check the key type and length, and catch revoked or malformed records before they break authentication.
No account needed. Domains and selectors are used for the lookup and never stored.
Common selectors to try
These are examples only — the correct selector depends on your email provider, and this tool cannot discover every possible selector automatically.
What DKIM is and how the record is used
DomainKeys Identified Mail proves a message really came from your domain and was not altered in transit.
What is DKIM?
Your sending server signs each outgoing message with a private key and adds a DKIM-Signature header. The matching public key is published in DNS under a selector. Receivers fetch that key and check the signature — if it verifies, the message is authentic and unmodified.
How the lookup works
Receivers read the d= (domain) and s= (selector) tags from the DKIM-Signature header, then query s._domainkey.d for a TXT record. That record contains v=DKIM1, an optional k= key type and the base64 public key in p=. This tool performs exactly that query.
Fixing common problems
Nothing found? The selector is usually wrong, or the record was pasted with line breaks — republish it as a single TXT value. Empty p=? The key is revoked. Testing mode t=y left on? Remove it, or receivers will ignore DKIM failures for your domain.
A worked example
For Google Workspace the selector is usually google, so the hostname is google._domainkey.example.com and the record reads v=DKIM1; k=rsa; p=MIIBIjANBg… A healthy record has a 2048-bit key, no t=y flag, and exists at exactly one hostname.
Check your email authentication
DKIM only tells half the story. Pair it with an SPF check to confirm your sending servers are authorized, and a DMARC check to see what receivers do when either one fails.
Frequently asked questions
Everything people usually ask about this tool.
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