What Is Dev Mode?
You should enable Cloudflare Dev Mode when you are testing changes to your website or trying to determine where an error is coming from.
Enable Dev Mode
To put Cloudflare on development mode, log in to the Cloudflare dashboard first here:
Click your domain on the main page (if you have many domains connected, make sure you click the right one for the site you’re working on).
Click Caching at the top menu bar:
Click Configuration in the sub-menu:
Scroll down until you see the Development Mode option, and turn it on by clicking the slider on the right:
When you’re done using Dev Mode, you can log back into your Cloudflare account and turn it off. Dev Mode will automatically disable on its own after 3 hours.