diff --git a/README.md b/README.md
index 1e6006d..bf44e7b 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,7 @@
     <a href="https://github.com/gwleuverink/bundle/actions/workflows/browser-tests.yml"><img src="https://github.com/gwleuverink/bundle/actions/workflows/browser-tests.yml/badge.svg" alt="browser-tests" style="max-width: 100%;"></a>
     <a href="https://github.com/gwleuverink/bundle/actions/workflows/codestyle.yml"><img src="https://github.com/gwleuverink/bundle/actions/workflows/codestyle.yml/badge.svg" alt="codestyle" style="max-width: 100%;"></a>
     <a href="https://codecov.io/github/gwleuverink/bundle"><img src="https://codecov.io/github/gwleuverink/bundle/graph/badge.svg?token=ZLFQ76HKRQ"/></a>
+    <a href="https://phpsandbox.io/n/uqpld"><img src="https://phpsandbox.io/img/brand/badge.png" height="20" alt="Bundle Sandbox"></a>
 </p>
 
 <br />
diff --git a/docs/_includes/nav_footer_custom.html b/docs/_includes/nav_footer_custom.html
index c868118..7a5184b 100644
--- a/docs/_includes/nav_footer_custom.html
+++ b/docs/_includes/nav_footer_custom.html
@@ -1,3 +1,7 @@
 <div class="site-footer">
+    <a href="https://phpsandbox.io/n/uqpld" class="mb-3">
+        <img src="https://phpsandbox.io/img/brand/badge.png" height="20" alt="Bundle Sandbox">
+    </a>
+
     Made with ❤️ by <a href="https://twitter.com/gwleuverink" target="_blank">@gwleuverink</a>
 </div>