# Immutable.js devtool extension

> Makes Immutable JS objects more readable when they are logged to the console.

Canonical page: [https://chrome-stats.com/d/immutable-js-devtool-extension](https://chrome-stats.com/d/immutable-js-devtool-extension)

## Overview

- **ID:** `immutable-js-devtool-extension`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Available
- **Publisher:** Julien Deniau
- **Category:** web-development
- **Daily users:** 3
- **Version:** 2.1.8
- **Last updated:** 2026-08-26
- **First published:** 2025-04-28
- **Size:** 51 KB
- **Data as of:** 2026-09-07
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/immutable-js-devtool-extension/)
- **Website:** [https://github.com/immutable-js/immutable-devtools/](https://github.com/immutable-js/immutable-devtools/)

## Description

The Immutable library is fantastic, but inspecting immutable collections in browser's Dev Tools is awkward. You only see the internal data structure, not the logical contents. For example, when inspecting the contents of an Immutable List, you'd really like to see the items in the list.

Chrome (v47+) and Firefox (116+) has support for custom "formatters". A formatter tells browser's Dev Tools how to display values in the Console, Scope list, etc. This means we can display Lists, Maps and other collections, in a much better way.

## Rankings

- #57,648 — Overall
- #196 — console

## Permissions and access

### Content script matches

- `*`

## Safety

- **Risk impact:** Moderate risk impact
- **Risk likelihood:** Moderate risk likelihood

### Analysis details

- Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
- This extension was recently updated in the past month. New updates may not be stable or safe.

> Some risk analysis details are omitted from this free response. [Upgrade to view the full analysis](https://chrome-stats.com/pricing).

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Source: [Chrome-Stats](https://chrome-stats.com/d/immutable-js-devtool-extension)