diff --git a/README.md b/README.md
index e9bea99c..651c9a82 100644
--- a/README.md
+++ b/README.md
@@ -708,6 +708,7 @@ Table of Contents
   * [mail.tm](https://mail.tm) — Disposable e-mail with user friendly interface. No registration needed.
   * [mailazy.com](https://mailazy.com/) — Mailazy is the only simple transactional email service you’ll need. 15,000 emails/month free forever (500 emails/day sending limit).
   * [mail-tester.com](https://www.mail-tester.com) — Test if email's dns/spf/dkim/dmarc settings are correct, 20 free/month
+  * [dkimvalidator.com](https://dkimvalidator.com/) - Test if email's dns/spf/dkim/dmarc settings are correct, free service by roundsphere.com
   * [mailboxlayer.com](https://mailboxlayer.com/) — Email validation and verification JSON API for developers. 1,000 free API requests/month
   * [mailcatcher.me](https://mailcatcher.me/) — Catches mail and serves it through a web interface
   * [mailchimp.com](https://mailchimp.com/) — 2,000 subscribers and 12,000 emails/month free