What is a Firefox extension package?

Firefox extensions are usually manifest-driven packages distributed as .xpi or .zip archives, or as raw manifest.json files. The manifest defines the extension name, permissions, icons, version constraints, and other metadata.

Because Firefox extensions are declared through metadata first, you can inspect a lot of useful information without loading the add-on into the browser.

Tool description

This tool inspects Firefox extension files and summarizes the manifest and archive metadata. It accepts .xpi, .zip, or raw manifest JSON and presents the important fields in a readable format.

Use it to review permissions, Gecko ID settings, version requirements, and localized metadata before opening the package manually.

Examples

  • A packaged .xpi extension
  • A zipped extension bundle with manifest.json
  • A raw manifest JSON file from an unpacked add-on

Features

  • Detects whether the source is an archive or a manifest file
  • Resolves localized names and descriptions from _locales
  • Shows icon previews and the raw manifest content

Limitations

This is a metadata inspector only. It does not execute extension code or validate runtime behavior.

The report only includes fields present in the package and manifest, so unusual or incomplete archives may produce partial results.