diff --git a/README.md b/README.md
index 31b1a38f..63e969e5 100644
--- a/README.md
+++ b/README.md
@@ -250,6 +250,7 @@ Table of Contents
   * [dnsspy.io](https://dnsspy.io) — Monitor your DNS and get alerts for changes, RFC-violating DNS configs, ... Free for 1 domain, open source maintainers may apply for a free premium account.
   * [monique.io](https://monique.io) — Create dashboards directly from SQL results, JSON data, API respones, Unix commands' output. Define alarms in Javascript. Free for 25000 submissions per month.
   * [assertible.com](https://assertible.com) - Automated API testing and monitoring. Free plans for teams and individuals.
+  * [letsmonitor.org](http://letsmonitor.org/) - TLS certificate expiration and connectivity monitoring with email and SMS alerts.
 
 ## Crash and Exception Handling