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HTML Editor

HTML Editor — runs in your browser. Inputs are not stored.

Runs in your browser No sign-up Free to use


HTML source · preview

Preview in an iframe sandbox that blocks scripts and forms.

How to use

  1. Type a document or fragment in HTML source.
  2. Press Preview to render it in the Preview (sandbox) frame below.
  3. Scripts and forms do not run or submit because of sandbox limits.
  4. Check layout only, edit the source, then press Preview again.
  5. Reset clears the source and reloads an empty document in the frame. There is no copy button.

Key concepts

The HTML editor is a sketch pad with source and preview on one screen. Preview writes the document into an isolated frame with a strict sandbox: no script execution, form submit, or same-origin access. It is a good fit for banner mockups or table markup. It does not replace full DevTools; interactive apps belong on a local server. Even empty source, once previewed, replaces the previous picture with a blank document.

Until you press Preview, the frame may be empty or still show the last result—always press the button after edits. This editor does not save files or upload source. External image URLs may still load over the network, but page scripts are blocked. Pair it with a validator or formatter to split structure checks from visual checks. There is no copy button; select the source text yourself.

Example

Put <h1>Preview</h1><p>Hello</p> in the source and press Preview: the frame shows a heading and a paragraph. A script tag still does not run because of the sandbox. After edits, press Preview again so the frame updates. Reset returns to an empty document.

Related: HTML formatter · HTML validator · Excel → HTML table

Frequently asked questions

Does JavaScript run in the HTML editor preview?

No. The frame sandbox blocks scripts and forms; it is for mockup review only.

Does the preview update on every keystroke?

No. The frame updates only when you press Preview. Reset also redraws an empty document.

Is there a copy button?

No. Select the source text yourself. Preview is for on-screen checking only.

Do remote images appear in preview?

If the URL is valid, images may load. Script-based widgets are still blocked.

Is source saved on a server?

No. Source and frame updates stay in the browser. Reset clears the field.

What happens to the frame after Reset?

Source is cleared and an empty document is loaded, so the previous preview disappears.

HTML Editor cover image

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Your input is not sent to the server and disappears when you close the page.

Last reviewed: 2026-09-04