DKIM Checker
Look up the DKIM public key of a domain by selector, or try common selectors, and check the key size. This live check sends only the domain name you enter to Google Public DNS (or Cloudflare DNS as a fallback) over HTTPS; nothing is sent to ToolkitPoint.
How to use DKIM Checker
- Type the domain that sends the email.
- Enter the DKIM selector, or leave it empty to try common ones.
- Press "Check DKIM".
- Read the record, the key type and the RSA key size for each selector found.
What DKIM Checker does
Look up the DKIM public key of a domain by selector, or try common selectors, and check the key size.
Pasted-markup tools run locally. Live URL and domain checks use the rate-limited ToolkitPoint server and only contact public destinations. For DKIM Checker, the operation is specifically to look up the DKIM public key of a domain by selector, or try common selectors, and check the key size.
Worked example
Check github.com with selector google. The tool finds the TXT record at google._domainkey.github.com, shows k=rsa and the public key, and reports the RSA key size calculated from the key itself. Try gmail.com with selector 20230601 to see how a revoked key (empty p=) is reported.
When DKIM Checker is the right tool
- Confirming DKIM is published after setting up a new email provider.
- Auditing key strength before a security review.
How to verify the result
Compare the finding with the live page source and the relevant search-engine documentation before changing a production site. The final DKIM Checker output should visibly match this goal: Look up the DKIM public key of a domain by selector, or try common selectors, and check the key size.
Important limitations
DNS has no list of a domain's selectors, so keys under uncommon selectors are only found when you enter the selector.
A free DKIM Checker alternative
People looking for DKIM Checker often compare products such as Ahrefs, Semrush. ToolkitPoint is not affiliated with those services. This page keeps look up the dkim public key of a domain by selector, or try common selectors, and check the key size free and available without an account; features, limits, and policies on other products can change, so compare their current product pages before choosing.
Last updated: September 15, 2026
Frequently asked questions
Where do I find my DKIM selector?
Open an email sent from the domain, view the original message, and find the DKIM-Signature header. The value after s= is the selector, for example s=google or s=selector1.
Why wasn't my key found without a selector?
DNS does not list a domain's selectors, so the tool can only try well-known names used by Google, Microsoft 365, Mailchimp and others. Enter your selector to check it directly.
What key size should DKIM use?
2048-bit RSA is recommended. 1024-bit keys still work at most receivers, and keys shorter than 1024 bits are often ignored.
What does an empty p= mean?
An empty public key means the key was revoked on purpose. Mail signed with that selector will fail DKIM.
Is the check private?
Only the selector and domain name are sent to Google Public DNS (or Cloudflare). The key size is calculated in your browser.