⚡ Free Browser Tool • Private Preview • No Login • No Install

HTML Viewer Online — Free HTML Editor & Live Preview Tool

HTML Viewer Online lets you paste, edit, run and preview HTML code instantly in your browser. Use the live preview, full screen preview, HTML formatter, validator, minifier, mobile preview and import/export tools without creating an account.

Live

HTML Preview

Code Uploads

Free

Browser Tool

Full

Screen Mode

Registration

What is HTML Viewer Online?

An HTML viewer online is a browser-based tool that renders HTML source code into a live webpage preview. Instead of saving a file, opening it manually and refreshing again and again, you can paste your HTML code, click Run and see the output immediately.

This tool is useful for students, developers, content teams and anyone who needs to quickly test HTML, CSS and JavaScript snippets. It also works well for previewing AI-generated HTML code before using it in a website, email template or project.

HTML Viewer Online: key facts

Free to use
No account required
No installation
Runs in your browser
Live HTML preview
CSS support
JavaScript support
Responsive device preview
Open local HTML files
Save / download as .html
Draft saved in your browser
Preview runs in a sandbox

Full Screen HTML Viewer

Use Full Page mode when you need a clean full screen HTML preview without the editor beside it. This is helpful for checking landing pages, HTML email layouts, AI-generated designs, printable pages and responsive sections in a larger view.

Preview rendered HTML in a distraction-free full page overlay
Open the preview in a separate browser tab with New Tab, then use its Print / Save as PDF button
Switch between desktop, laptop (1024 × 768), tablet (768 × 1024) and mobile (390 × 844) preview sizes
Save a PNG screenshot of the rendered preview

HTML Viewer Online features

Live HTML Preview

Paste HTML code and see it render as you type, or press Run.

HTML Editor

Write and edit HTML with syntax highlighting, line numbers, undo/redo, find & replace and word wrap.

Full Screen Preview

Open the output in a clean full page overlay or in a new browser tab.

HTML Formatter

Beautify messy HTML code with automatic indentation.

HTML Minifier

Compress HTML by removing unnecessary whitespace and comments.

Basic HTML Validator

Check common markup issues such as missing title, viewport or unbalanced tags.

Mobile Preview

Test the same HTML in desktop, laptop, tablet and mobile sizes.

Import & Save

Open local HTML files by import or drag and drop, and save your edited code back to your device.

What each tool does

Tool	What it does	Good to know
Run / Auto-run	Renders the editor code in the preview	Auto-run updates shortly after you stop typing; turn it off for heavy scripts
Format	Re-indents HTML, CSS and JavaScript	Uses the open-source js-beautify library
Minify	Removes comments and extra whitespace	A simple whitespace minifier, not a full optimiser
Validator	Basic HTML checks	Not a W3C validator — see the list of checks below
Accessibility	Basic accessibility checks	Does not check colour contrast
Console	Shows `console.log`, warnings and JavaScript errors from the preview	Cleared on each run
Meta/OG Preview	Shows the title, description and Open Graph card from your code	Reads your tags; does not fetch a live URL
Device preview	Desktop (full width), 1024 × 768, 768 × 1024, 390 × 844	Sizes are CSS pixels; the current size is shown above the preview
Screenshot	Saves the preview as a PNG image	Drawn in your browser with the html-to-image library; images from sites that block sharing may be left out
Share	Creates a link that contains your code	Very long code makes very long links
History	Keeps up to 20 snapshots of this session	Session only; the latest draft is also autosaved

Open an HTML file online

Click Import or drag a file from your computer onto the editor. The file is read by your browser on your own device and rendered in the preview straight away; it is not uploaded. Supported files: .html, .htm, .xhtml, .svg and .txt.

Only the single file you open is loaded. If the page links to other local files — a style.css, a script.js or images in a folder next to it — those cannot be read by the preview. Paste the CSS and JavaScript into the page, or use full https:// links.

How to use this HTML viewer

1. Paste HTML

Paste your HTML code into the editor, import a local .html file or drag it onto the editor.

2. Run

The preview updates as you type. You can also press Run or Ctrl+Enter (⌘+Enter on Mac).

3. Format or validate

Use Format, Minify, Validator, Accessibility, Console and Meta/OG panels when required.

4. Preview full screen

Use Full Page, New Tab or the device buttons to test the output at different sizes.

Keyboard shortcuts

Action	Windows / Linux	Mac
Run preview	Ctrl + Enter	⌘ + Enter
Download HTML	Ctrl + S	⌘ + S
Find & replace	Ctrl + H	Find button
Undo / redo	Ctrl + Z / Ctrl + Y	⌘ + Z / ⌘ + Shift + Z
Close dialog or full screen editor	Esc	Esc

Preview AI-generated HTML code

If you generate HTML using ChatGPT, Gemini, Claude or another AI coding tool, paste the code here and preview it instantly. You can format the code, check basic validation issues, read JavaScript errors in the Console, open the output in full screen mode and test how it looks on mobile widths.

This makes the tool useful for quick experiments, landing page drafts, small components, email layouts, CSS snippets and learning projects. If you have a whole chat answer with code blocks, the AI-generated HTML preview page pulls out the code, joins separate HTML, CSS and JavaScript blocks and lists files the page will not be able to load.

Basic HTML checks (not a full W3C validator)

The Validator tab runs quick checks in your browser. It does not replace the W3C Markup Validation Service. It reports:

Missing <!DOCTYPE html>, <html>, <head> or <title>
Missing charset, viewport or meta description tag
Missing lang attribute on <html>
Deprecated elements such as <font>, <center> and <marquee>
Tags opened and closed a different number of times
Images without an alt attribute

Accessibility checks

The Accessibility tab checks for:

Images without an alt attribute
Buttons with no text or label
Links with no text or label
Form fields without a label
Skipped heading levels (for example <h2> followed by <h4>)
Missing lang attribute on <html>

It does not measure colour contrast or test with a screen reader, so treat a clean result as a first pass, not a full audit.

Privacy and security

Your code stays in your browser. Editing, formatting, checking, previewing and screenshots all happen on your device. Imported files are read locally.
Your draft is saved in your browser only (local storage), so it survives a page refresh. Clearing browser data removes it, and the Clear button empties the editor.
Share links contain the code itself, after the # sign. The part after # is not sent to our server, but anyone who has the link can read the code, so do not share links that contain passwords or private data.
The preview runs in a sandboxed frame. Code in the preview cannot read or change this page, and cannot navigate this tab. Pop-ups it opens stay sandboxed too.
Analytics never receive your code. We use Google Analytics to count page visits and which buttons are used (for example "format" or "screenshot"). Your HTML, file names and share links are not sent.

Limitations and common mistakes

Relative file paths do not load. <img src="images/logo.png"> or <link href="style.css"> point to files on your computer that the preview cannot see.
External files need internet access, and some sites block their images or fonts from being used elsewhere.
Only HTML, CSS and JavaScript run. PHP, Python and other server-side code are shown as text or ignored.
Plain http:// resources may be blocked because this page is served over HTTPS.
The validator and accessibility checks are basic, as listed above.
Very large files (several MB) can make the editor slow; turn off Auto-run for them.
Long share links can be cut off by some chat apps and email clients. Use Save for large pages.

Common use cases

Students learning HTML

Practice tags, tables, forms, CSS and layout snippets without installing a code editor.

Developers testing snippets

Quickly test HTML, CSS and JavaScript snippets before adding them to a project.

HTML email preview

Check email template structure and visual output before sending or exporting.

Content and SEO teams

Review headings, meta tags, Open Graph tags and simple page sections visually.

Frequently asked questions

What is HTML Viewer Online?

It is a free browser-based tool to paste, edit, run and preview HTML code instantly with live preview and formatting tools. No account or installation is needed.

How do I open an HTML file online?

Click Import or drag the file onto the editor. HTML (.html, .htm), XHTML, SVG and plain-text files are read by your browser on your own device and rendered in the preview.

Is my code uploaded to a server?

No. Editing, formatting, checking and previewing all happen in your browser, and your draft is saved only in your browser's local storage. If you use Share, the code is placed inside the link itself after the # sign. It is not stored on our server, but anyone who has the link can read the code.

Why are my images or CSS files not showing?

The preview only sees the code in the editor. Files referenced with relative paths such as images/logo.png or style.css stay on your computer and cannot load. Use full https:// URLs, put the CSS inside a style tag, or embed small images as data URIs.

Can I preview HTML in full screen?

Yes. Click the Full Page button to open the rendered output in a clean full screen preview.

Can I format HTML online?

Yes. Use the Format button to beautify and indent messy HTML code automatically.

Is the validator a full W3C validator?

No. It runs quick basic checks for common problems such as a missing doctype, title, charset or viewport, deprecated tags, unbalanced tags and images without alt text. For full standards validation, use the W3C Markup Validation Service.

Can I preview AI-generated HTML?

Yes. Paste HTML generated by an AI tool and use Run, Format, Validator, Console, Full Page and Mobile Preview to test it. The AI HTML preview page can also pull the code out of a full chat answer with code fences.

Is my work saved if I refresh the page?

Yes. The editor keeps a draft in your browser's local storage and restores it when you come back on the same device and browser. Clearing browser data or using a private window removes it.

Does it work on mobile?

Yes. The page works in modern mobile browsers, lets you switch between the editor and the preview, and includes a dedicated mobile preview width.