Put HTML onto one tag per line with nesting indentation, so a minified page becomes readable again.
<div><p>Hello</p><ul><li>One</li><li>Two</li></ul></div>
<div>
<p>Hello</p>
<ul>
<li>One</li>
<li>Two</li>
</ul>
</div>
No. It is treated as text throughout and never inserted into the page, so nothing in it can run.
No. This tool runs entirely in your browser — nothing you type or paste is uploaded, logged or stored anywhere.
There is no fixed limit. Very large documents depend on your device’s memory, but ordinary pages and files are handled instantly.