Online developer tool

CodePen

Sketch front-end ideas in a live-code style workspace.

Input

<h1>Hello UI</h1>
<style>h1{color:#2563eb}</style>

Output

Run the tool to see output here.

How to use CodePen

Sketch front-end ideas in a live-code style workspace.

Paste a short code sample, run CodePen, and review the result before copying it.

Use multiple lines when the task supports it, then download the output as a text file.

Category	code
Best for	Quick browser-side formatting, conversion, inspection, and drafting workflows.
Output	Readable text output that can be copied, downloaded, or used as a starting point.
API ready	The page is structured so a real processor or AI API can replace the MVP logic later.

Is CodePen free to use?

Yes. This page is available as a free browser-based MVP tool.

Does this page call a real AI API?

Not yet. The current implementation is interactive front-end logic or mock output, with a structure ready for a real API later.

Can I copy the result?

Yes. Run the tool, then use the copy button in the output panel.