GitHub HTML Preview

About

GitHub HTML Preview adds a one-click Preview button to any .html file page on GitHub, so you can see how it renders without downloading it, setting up GitHub Pages, or leaving your browser.

Why this exists AI tools now write a lot of HTML including docs, diagrams, interactive demos, one-off visualizations that are often committed by people who don't otherwise write HTML for a living and are still learning their way around GitHub. Copy-pasting into a separate renderer every time you want to check one is slow. This previews the file right where it already lives, in one click, so you can iterate on AI-generated visuals and interactive components as fast as you can regenerate them.

How it works Open any .html or .htm file on GitHub and click Preview. The page you're already looking at is rendered right where the source code was with tabs, buttons, and scripts working, scrolling naturally in both directions, like a real embedded page. Click Code to switch back, and toggle as many times as you like. Prefer it automatic? Turn on auto-preview from the toolbar icon and matching files render the instant you open them.

Built for privacy and safety from the ground up

No sign-in, no account, no API token required.
Nothing ever leaves your browser, and the extension talks to no server other than GitHub itself: it reads the file content already shown on the page (with a last-resort fallback that fetches the file's own github.com raw URL when the on-page text isn't extractable). The previewed file may load the images, styles, and scripts it references, exactly like it would as a normal webpage.
Scripts run in a locked-down sandbox with no identity. The previewed page cannot read your GitHub session or cookies, touch the GitHub page you're on, access this extension's data, or navigate your tab. It renders in an isolated frame with a throwaway origin.
Auto-preview asks before running scripts. If a file contains scripts, auto-preview shows a warning instead of rendering and it runs only when you click Preview. And if you'd rather scripts never run at all, one toggle in the popup renders every preview with scripts disabled entirely.
One permission, and it's a small one. Storage: used only to remember your two settings. Nothing else.
Built to preview your own files but be careful with anyone else's. We built this to check our own AI-generated HTML faster, not to make it easier to run code from repos you don't control. Nothing is "processed" by us. There's no server and no one reviewing what you preview; it all happens locally in your browser, which means the judgment call of clicking Preview on a file with scripts is entirely yours. The sandbox stops a previewed page from touching your GitHub session, cookies, this extension's data, or your tab, but inside its own frame it can still do anything a webpage's script can do. Take the script-consent warning seriously: only click through on code you wrote yourself or otherwise trust. If you don't recognize or understand what a file's script does, don't preview it and view the source instead.

Works with private repositories too and anything you can already view on github.com, you can preview.

Built by https://bauerautomate.com