Firefox Developer Tools
The facts below are what the maker publishes about Firefox Developer Tools, checked and dated. Our editors have not written about it yet.
Plans and prices
From Firefox Developer Tools's own pricing page, checked 12 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Firefox Developer Tools | Free | Built into Firefox · examines, edits, and debugs HTML, CSS, and JavaScript |
The facts
Each one read from Firefox Developer Tools's own pages, with the date it was checked.
What it does
- Accessibility
- The Accessibility Inspector exposes a page’s accessibility tree to help identify missing information or other issues.checked 12 Oct 2026
- Accessibility performance note
- When enabled, the accessibility engine runs in the background and may affect other panel metrics and overall browser performance.checked 12 Oct 2026
- Additional tools
- Built-in tools include Memory, Storage Inspector, Style Editor, screenshot, rulers, and JavaScript tracing features.checked 12 Oct 2026
- AI integration
- The docs list Firefox DevTools MCP, an MCP server that enables AI assistants to automate and interact with Firefox.checked 12 Oct 2026
- Configuration
- Developer Tools can be docked at the bottom or side of the browser window or opened in a separate window.checked 12 Oct 2026
- Developer audience
- Firefox Developer Edition is described as a browser made for developers and includes developer tools in beta.checked 12 Oct 2026
- Extension support
- The documentation describes extending Firefox DevTools through browser extensions.checked 12 Oct 2026
- JavaScript debugger
- The JavaScript Debugger lets users step through code and examine or modify its state to track down bugs.checked 12 Oct 2026
- Limit of network simulation
- Responsive Design Mode says its network throttling is approximate and should not be relied on for exact performance measurements.checked 12 Oct 2026
- Network Monitor
- The Network Monitor shows HTTP requests, their durations, and request details.checked 12 Oct 2026
- Open source
- Yeschecked 21 Sep 2026
- Page Inspector
- The Page Inspector examines and modifies a page’s HTML and CSS, including its box model, fonts, animations, and layouts.checked 12 Oct 2026
- Purpose
- Firefox Developer Tools are built into Firefox and let web developers examine, edit, and debug HTML, CSS, and JavaScript.checked 12 Oct 2026
- Remote debugging
- DevTools can connect to targets in other browsers or devices, including Firefox for Android.checked 12 Oct 2026
- Responsive testing
- Responsive Design Mode simulates device screen sizes, pixel density, touch, and network conditions to test how a site looks and behaves.checked 12 Oct 2026
- Storage
- The Storage Inspector can inspect cookies, local storage, IndexedDB, and session storage on a page.checked 12 Oct 2026
Where it runs
- Browser and add-on debugging
- The Browser Console displays messages from the browser and add-ons and can run JavaScript in the browser’s scope.checked 12 Oct 2026
- Browser debugging
- The Browser Console displays messages from the browser and add-ons and can run JavaScript in the browser’s scope.checked 12 Oct 2026
- Browser engine
- geckochecked 21 Sep 2026
- Supported download platforms
- Firefox Developer Edition download options listed include Windows, macOS, and Linux builds.checked 12 Oct 2026
- Supported platforms
- desktopchecked 21 Sep 2026
- Web app debugging
- The Application panel includes tools for inspecting and debugging progressive web apps, service workers, and web app manifests.checked 12 Oct 2026
Money
- Free plan
- Yeschecked 21 Sep 2026
The company
- Maker
- Mozilla says Mozilla Corporation makes Firefox and was established in August 2005 as a wholly owned taxable subsidiary of Mozilla Foundation.checked 12 Oct 2026
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