I added a couple of features and improvements to ASCII Smuggler, including:

• Optional rendering of the BEGIN and END Unicode Tags when crafting hidden text
• Added a feature to URL decode the input before checking for hidden text
• Output Modes for Decoding: Switch between highlighting the hidden text amongst the regular content, or only showing the hidden text in the output
• The selected options are remembered now (using local storage)
• Updated the UI to make it look nicer (e.g bigger fonts), and it works better on mobile now

The tool is here.

Happy hacking.