Free DKIM checker
Check the DKIM keys of any domain
Enter a domain to look up DKIM keys at the selectors Google Workspace, Microsoft 365 and other providers use, or enter selector._domainkey.example.com to check one selector.
How it works
How DKIM works
The sending server hashes the message body and selected headers, signs the hash with its private key and adds a DKIM-Signature header. The header names the signing domain (d=) and the selector (s=). The receiver fetches the public key from DNS and verifies the signature.
A valid signature proves the message was not changed and was signed by someone with access to the domain's DNS. For DMARC to pass on DKIM, the signing domain must match the domain in the visible From address.
- v
- Version, always DKIM1
- k
- Key type: rsa (default) or ed25519
- p
- The public key. Empty means the key is revoked
- t
- Flags: y for testing, s for no subdomains
FAQ
DKIM checker FAQ
Common questions about DKIM keys and selectors.
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Check the DKIM keys of any domain
Find the DKIM keys of any domain. We look up common selectors or the one you enter, and check the key type, key length and testing flag.