https://litelink.at/promke

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<p>This is display.cgi (<a href="display.py">source</a>).
It takes some text you enter into a form, and displays it for you
as HTML. This is a great way to see how some HTML code looks in your
(or someone else's) browser. So paste 'n go:</p>
<form method="get" action=""><textarea rows="40" style="width: 100%; height: 75%" name="t">https://litelink.at/promke</textarea>
<input type="submit" /></form>