diff --git a/bundles/org.openhab.transform.regex/README.md b/bundles/org.openhab.transform.regex/README.md
index 73ea4c92006..4c76f8d0b98 100644
--- a/bundles/org.openhab.transform.regex/README.md
+++ b/bundles/org.openhab.transform.regex/README.md
@@ -105,3 +105,4 @@ Please note: This profile is a one-way transformation, i.e. only values from a d
     * [Regex 101](https://regex101.com/)
     * [Regex R](https://regexr.com/)
     * [ExtendsClass](https://extendsclass.com/regex-tester.html)
+    * [Softwium](https://softwium.com/regex-explainer/)