GitHub HTML Preview

Run and compare commit-pinned public and private HTML directly on GitHub

Preview HTML files and pull request changes directly on GitHub. GitHub HTML Preview adds lightweight Code and Preview controls to HTML blobs, pull requests, commits, and comparisons. It renders commit-pinned HTML in an isolated sandbox, resolves repository-relative assets at exact refs, and supports side-by-side review of edited files with synchronized scrolling. Features include public and private repository previews through your signed-in GitHub session; added, removed, and edited pull-request file previews; full-page previews; durable numbered annotation pins linked to GitHub PR comments; automatic retries for transient failures; and visible diagnostics for unresolved resources. Privacy: no tracking, analytics, ads, external account, GitHub token storage, or password storage. Private repository access stays in your existing github.com session. Preview content is isolated from GitHub and extension APIs. Executable HTML can make network requests, like opening the page itself, so preview only code you trust.