# Chrome extension source viewer (CRX Viewer)

> Browser extension and web page by Rob Wu for inspecting packaged browser extensions without installing them. On Chrome Web Store, Opera, Firefox, Thunderbird and Microsoft Edge add-on pages it adds a button that downloads the package as a zip or opens it in a viewer, and links to extension packages hosted elsewhere can be opened as well. The viewer reads CRX, NEX, XPI and ZIP files: it lists and filters files, searches content by string or regular expression, beautifies and syntax-highlights code, previews images, opens nested zips, shows per-file hashes and derives the extension ID from the package key, signature or manifest.

- Type: Tool
- Targets: Website
- Category: Website analysis tools
- Relationship: Foundation tool
- Sources reviewed: 2026-10-19
- Added to the catalog: 2026-11-01
- Original resource: <https://github.com/Rob--W/crxviewer>
- Primary source: <https://github.com/Rob--W/crxviewer/blob/c1a0a7f63983600a960e3d02d8a36c4142c7cca4/README.md>
- Catalog page: <https://awesomerea.org/resources/crxviewer/>
- Record JSON: <https://awesomerea.org/resources/crxviewer/record.json>
- Chinese version: [简体中文](https://awesomerea.org/zh/resources/crxviewer/index.md)

## Requirements & limits

- Version 1.7.1, committed on 2026-09-01 as the reviewed master head, is the version in all three manifests: Manifest V3 builds for Chrome 88+ and Opera 74+, and a Manifest V2 build for Firefox 115+. The repository has no tags or releases; the README links the Chrome Web Store, Opera and addons.mozilla.org listings and an online demo page that opens local files or URLs.
- Store listings are the documented install route; the README gives no build instructions. make.js builds the Chrome, Opera, Firefox and web packages with shelljs and the less compiler from npm and zips them with 7z.
- The extension requests tabs, storage, context-menu, downloads and declarativeContent permissions and access to Google's CRX download endpoints, and asks for optional access to all sites before fetching packages hosted elsewhere. Its Firefox build routes addons.mozilla.org requests through services.addons.mozilla.org, a workaround the source documents for Firefox's restrictions on add-ons reading some Mozilla domains and still uses for non-public XPI files such as developer submissions.
- The viewer shows package contents as published: beautification only reformats code and does not reverse obfuscation. Downloaded extensions keep their authors' rights and store terms.
- MPL-2.0; bundled libraries such as zip.js, Prism, js-beautify and SparkMD5 keep their own licenses.

## Primary sources

1. <https://github.com/Rob--W/crxviewer/blob/c1a0a7f63983600a960e3d02d8a36c4142c7cca4/README.md>
2. <https://github.com/Rob--W/crxviewer/blob/c1a0a7f63983600a960e3d02d8a36c4142c7cca4/src/manifest.json>
3. <https://github.com/Rob--W/crxviewer/blob/c1a0a7f63983600a960e3d02d8a36c4142c7cca4/src/manifest_firefox.json>
4. <https://github.com/Rob--W/crxviewer/blob/c1a0a7f63983600a960e3d02d8a36c4142c7cca4/src/lib/crx-to-zip.js>
5. <https://github.com/Rob--W/crxviewer/blob/c1a0a7f63983600a960e3d02d8a36c4142c7cca4/src/crxviewer.js#L997-L1056>
6. <https://github.com/Rob--W/crxviewer/blob/c1a0a7f63983600a960e3d02d8a36c4142c7cca4/src/domain-fronter.js>
7. <https://github.com/Rob--W/crxviewer/blob/c1a0a7f63983600a960e3d02d8a36c4142c7cca4/make.js>
8. <https://github.com/Rob--W/crxviewer/blob/c1a0a7f63983600a960e3d02d8a36c4142c7cca4/LICENSE>

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## About this entry

The description was reviewed against primary sources.
Original editorial content: MIT. Linked projects, papers and assets retain their own rights and licenses.