MobiDevTools by Francesco De Stefano

Real developer tools on your phone. MobiDevTools adds a full DevTools panel to any page in Firefox for Android — and works just as well on desktop. Tap the toolbar button and inspect, debug and audit the page you are looking at. No computer, no cable, no adb.

Panels

• Console — every console message, error and promise rejection of the page, captured from the first line (works on strict Content-Security-Policy sites). Expandable objects, autocomplete on the page's real objects, top-level await, $0 / $$ / copy() / inspect(), console.table, %c styles, preserve log.
• Elements — live DOM tree with element picker; the real matched CSS rules (source file, @media, overridden declarations) editable live; computed styles and box model; addEventListener listeners with the line that added them; CSS Grid and Flexbox overlays; edit as HTML.
• Network — every request (documents, scripts, CSS, images, fetch/XHR), even those made before you opened the panel. Headers, payload, response body and JSON preview, timings, copy as cURL or fetch(), filters like status:404 or method:post, HAR export.
• Sources — all files of the page, fast even when huge or minified, one-tap pretty-print, find, snippets, download all sources as .zip. Watch expressions and logpoints.
• Pharos — Lighthouse-style audits of Performance, Accessibility, Best Practices and SEO, scored 0–100, with the exact elements to fix.
• React (and Preact), Vue and Angular — component trees, props, state, hooks, signals, Pinia/Vuex/router; edit state live. These tabs appear only on pages that use the framework.
• State — Redux, Redux Toolkit, Zustand, NgRx and every library that supports Redux DevTools: actions, state, diff, time travel.
• Application — edit localStorage, sessionStorage and cookies; browse IndexedDB, Cache Storage, manifest, service workers.
• Performance — FPS, Core Web Vitals (FCP, LCP, INP, CLS), navigation timing, slowest resources.

For developers

Add your own tabs with the plugin API — from an extension file or straight from your web app (window.MobiDevTools.registerPanel). The plugin guide is on the documentation website.

Privacy

Nothing leaves your device: no analytics, no telemetry, no remote code. The panel writes nothing into the sites you inspect, and it runs in an isolated shadow DOM that page scripts cannot read.

Permissions

• Access your data for all websites — to open the panel on any page you choose.
• Browser tabs and navigation — to keep the panel open across reloads.
• Network requests (webRequest) — to show the Network panel; response bodies are read-only and only in tabs where you opened the panel.
• Storage — your settings, snippets and console history.

Documentation, plugin guide and changelog: https://mobidevtools.sourceforge.io/
Free and open source (MIT): https://sourceforge.net/projects/mobidevtools/