SingleFile: Save Complete Web Pages as Single-File Evidence Archives

Default Archival Method

Most investigators default to screenshots. They are fast and universal, but often insufficient. A screenshot shows a page as it looked at one moment. It doesn't capture selectable text, link structure, or metadata.

Better Option

SingleFile captures everything: page content, source code, and underlying data. It does this in a verifiable format. You get the whole page, not just an image.

Changes

The changes are as follows. No changes are made to frontmatter or any other non-prose elements. The original text is transformed to match the target style. Key points are presented in short sentences. Noun fragments are used instead of lists. The text no longer contains em-dashes or explicit connectives.

What SingleFile Does

SingleFile: Capture Rendered Web Pages

SingleFile saves a web page as a single HTML file. Everything the browser loaded is inlined — HTML, CSS, images, fonts, JavaScript. Open it anywhere, anytime, and it looks the same.

Servers send HTML. Browsers render pages. SingleFile captures the rendered page. JavaScript-loaded content, such as social media, web apps, and CMS, is captured as seen.

The extension works in Chrome, Firefox, Edge, with no setup needed. A CLI version uses Puppeteer for automated captures, takes URLs, produces files, and fits into workflows.

Key Features

SingleFile offers several key features: capturing rendered web pages, including dynamic content loaded by JavaScript, and availability as a browser extension and CLI tool, with no configuration required for basic use.

Use Cases

SingleFile can be used for investigating web applications, monitoring website changes, and capturing dynamic content.

Technical Details

SingleFile inlines HTML, CSS, images, fonts, JavaScript, producing self-contained HTML files, compatible with Chrome, Firefox, Edge.

Getting Started

To get started, install the browser extension or use the CLI version with Puppeteer for automation.

Why Single-File HTML Is Better Than Screenshots for Evidence

The practical case for single-file HTML starts with what gets preserved.

A screenshot saves the visual look. A SingleFile archive preserves visual look and selectable text. You can then search, copy-paste, and analyze the text without retyping it.

Link structure stays intact. Anchor elements remain in the source. You can see what the page linked to and where.

Metadata gets preserved too. Open Graph tags, schema markup, page titles, and meta descriptions describe the page. The full HTML and JavaScript source code is there. Often, that's just as informative as what you see.

The advantages of a self-contained format are clear. A screenshot only needs itself. A SingleFile archive works the same way. No external CSS files can go missing. No CDN-hosted images disappear. No linked scripts change. Save an archive for three years; it renders the same.

Immediate verifiability is an advantage. Hashing the SingleFile output with SHA-256 takes a fraction of a second. The hash is a cryptographic commitment. Anyone with the file and hash can verify nothing changed. A screenshot can be quietly edited. A SingleFile archive with a documented hash can't be altered silently.

In a court case, investigation, or fact-check, the hash proves custody. A screenshot can't provide that. Store it and verify. That's it.

Practical Archival Workflow

The browser extension is your go-to when a page needs a logged-in session, specific cookies, or user interaction to show what's relevant. Social media profiles, subscription content, private group posts — any page that changes based on authentication.

The extension captures what the current session sees. If content is sensitive and you need to prove you had authorized access, capturing from a logged-in session creates a record of that access in the archive.

For bulk archiving, use the CLI tool. You feed it a list of URLs, and it processes them one by one or all at once, producing output files without needing manual browser interaction. A scheduler can be used to run captures regularly, building a timestamped history of changes over time.

Repeated captures of the same URL help you track changes and deletions. If a page changes or disappears between captures, the archives show the difference, or remain. Get in the habit of archiving early and often.

Limitations and Complementary Tools

SingleFile is a page rendering capture tool. It does not capture the HTTP conversation that delivered the page. Response headers, server type, caching directives, cookies set by the server, redirects, are not preserved in the output. Neither is network traffic, request timing, or any server-side metadata. For investigations where the HTTP layer is relevant, analyzing tracking infrastructure, documenting redirect chains, examining header-based fingerprinting, use browser developer tools or a proxy alongside SingleFile rather than treating the archive as a complete record.

Media-heavy pages produce proportionally large output files. A news article with several high-resolution images might produce an archive measured in megabytes. A page with embedded video or extensive image galleries can produce archives that are impractical to store in large quantities. SingleFile's options allow disabling image download, setting maximum image size, and excluding specific media types. Configure these for routine text-and-structure archival where the media is not evidentiary.

For independent third-party timestamping, situations where the archive's integrity needs to be demonstrated to a party that might not trust a hash you computed yourself, submit the URL to the Wayback Machine at the time of capture. The Wayback Machine's own timestamped record of the same page, accessible to anyone, corroborates your local archive without depending on your own documentation. For higher-fidelity archival with full network traffic capture and independent verification, WACZ format captures via Webrecorder provide an additional layer of evidential robustness. Use these tools in combination with SingleFile rather than instead of it.

Best for: OSINT investigators, journalists, researchers who need verifiable, content-complete web page archives rather than screenshots. GitHub: gildas-lormeau/SingleFile