The viewer above is the whole tool. Paste on the left, look on the right. It works with a full page from ChatGPT, Claude or Gemini, a snippet from a tutorial, or an email template you want to check before sending.
How to use the HTML viewer
- Paste your HTML in the left pane, or click Open file, or drop a
.htmlfile on it. - Watch the preview. It redraws a moment after you stop typing.
- Check it on a phone. Phone width shows the page at 390 pixels.
- Editing a script? Turn off Auto-run and use Run (or Ctrl or Cmd plus Enter), so a loop you are halfway through typing doesn't freeze the tab.
- Send it. When it looks right, ask for a link below the viewer.
On a phone the two panes become tabs: HTML and Preview.
Run HTML, CSS and JavaScript online
Scripts run. So do <style> blocks, inline SVG, canvas games and charts. If your page loads a library from a CDN (Tailwind, Chart.js, Three.js), the preview loads it too, as long as you are online.
Two things to expect:
- Files next to your HTML don't load. An
<img src="photo.jpg">points to a file on your computer that the viewer never sees. Use full URLs, or put the image inside the HTML. In a Hostus account you can upload images, video and fonts next to the page. - Saves are temporary. A page that saves to
localStorageworks, but it forgets everything when you edit the code or reload.
View an HTML file on your phone
Phones don't open .html files well. On an iPhone the Files app opens them in a quick preview, and Apple doesn't promise that the page's scripts run there. Open this page on the phone, tap Open file, pick the file, then switch to Preview. The full walkthrough is in how to open an HTML file on iPhone.
Is it safe to paste my HTML here?
The code runs only in your browser, inside a sandboxed frame. That frame can't read this site, its cookies or your other tabs, and it can't move the page you are on. Nothing is sent to a server while you paste and preview. The HTML leaves your browser only if you ask for a link.
The viewer never loads code from a web address. There is no link that opens this page with someone else's HTML already inside it.
Which HTML viewer should you use?
| Tool | Best for | What you get at the end |
|---|---|---|
| Hostus HTML viewer | A whole page you already have, from an AI or a file | A link to the page, which you can send, edit in place and see who read it |
| CodePen or JSFiddle | Writing code from scratch in separate HTML, CSS and JS panes | A pen or fiddle that shows the code next to the result |
| W3Schools Tryit | Learning one tag or property at a time | Nothing to keep |
| Your browser (File, Open) | A quick look on a computer | Only you can see it |
From preview to a link
Type your email under the viewer and ask for the link. We email you a sign-in link, and the page is waiting in your free Hostus account. From there you can:
- Send it as
your-page.hostus.page. Anyone opens it, no account needed. - Fix it later and keep the same link.
- See who opened it and how far they read.
- Collect what people type in a form on the page. It works with no setup.
Up to 1 MB goes from this page. Bigger pages go from your dashboard.