Before you install: MobX Developer Tools only shows data for apps that use MobX or mobx-state-tree. It does nothing on other pages.

Why it's a strong pick

MobX Developer Tools is hosted in the mobxjs GitHub organization. It is open source under the MIT license, and its code is public. It uses Manifest V3, Chrome's current extension format. The latest GitHub release we found is v0.9.33, from 17 June 2026, which made the extension work with Chrome 147.

What it does

The README describes DevTools for debugging MobX applications. You can track changes to observables, inspect the dependency tree and explore mobx-state-tree stores. The README lists compatibility with MobX 2.2 to 6.x.

Key features

Observable tracking. Track changes to observables.
Dependency tree. Inspect how your MobX values depend on each other.
mobx-state-tree stores. Explore them; this needs the companion mobx-devtools-mst package and makeInspectable(store) in your app.
Keyboard shortcut. Alt+M moves the DevTools window to the left.
Standalone app. For browsers without extension support, the README offers npm install --global mobx-devtools.

Who it's for

MobX Developer Tools is for developers who use MobX or mobx-state-tree and want to see what changes and why. It is not for people who only browse the web.

What permissions does MobX Developer Tools ask for?

Its manifest asks for contextMenus, storage and scripting, plus access to all sites. It injects a content script into every page's main world at document start, so it can hook MobX. It needs Chrome 88 or newer. This is a broad list, so read the install prompt before you add it.

Do I need to change my app?

Only for mobx-state-tree, going by the README. For plain MobX, the README describes tracking observables and the dependency tree. For mobx-state-tree stores, you add the mobx-devtools-mst package and call makeInspectable(store). Check the README for the setup steps that match your MobX version and your Chrome version.

Can I trust its privacy?

We could not read the developer's privacy policy when we checked; read it before installing. The manifest asks for access to all sites and injects a script into every page at load. Because of that, install it only if you work with MobX, and read the policy first.

How often is it updated?

Not often. The v0.9.33 release is dated 17 June 2026. The release before it was on 4 December 2024, so gaps can be long. These are GitHub release dates, not store dates, so the version in the store may differ from them.

FAQ

Does it work with mobx-state-tree? Yes, with the companion package and makeInspectable(store).

Which MobX versions does it support? The README says MobX 2.2 to 6.x.

Is it open source? Yes, under the MIT license.

Good to know

Honest limit: the repo went quiet from December 2024 to June 2026. If something looks off, check that your Chrome version and MobX version match what the README lists.

Other developer tools to compare

MobX Developer Tools is one of 13 picks in our developer tools guide:

Redux DevTools: debug Redux state.
Apollo Client Devtools: inspect Apollo Client apps.
Preact Developer Tools: inspect Preact components.
Lighthouse: audit a page.
JSON Formatter: read JSON responses.
React Developer Tools: inspect React components.
Vue.js devtools: inspect Vue 3 apps.
Requestly: redirect URLs, modify headers and mock requests while you test.
Solid DevTools: debug SolidJS reactivity.
Ember Inspector: inspect Ember.js apps.
Refined GitHub: Simplifies GitHub and adds 100+ small improvements for repos and pull requests. Works on GitHub.com only. Open source.
Header Editor: Rewrites request and response headers, redirects and blocks requests with rules you set. The Chrome build is the Lite version. Open source.