HTML Checking for Large Sites
Rocket Validator automatically checks your pages on the W3C Validator.
HTML issues tagged as async.
The async and defer boolean attributes of the <script> element control how an external script should be executed once it has been downloaded. The async attribute makes sense when an external script (defined with the src attribute) is loaded, or when defining a script of type module:
<script async src="app.js"></script>
<script type="module">
/* JavaScript module code here */
</script>Learn more:
25,000 HTML checks per month. Is that enough for your site?
Save time using our automated web checker. Let our crawler check your web pages on the W3C Validator.