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On the recordRead 12 Oct 202625 facts
Firefox Developer Tools
Plans and prices
Firefox Developer Tools
Free
Built into Firefox · examines, edits, and debugs HTML, CSS, and JavaScript
Read 12 Oct 2026 · firefox-source-docs.mozilla.org
On the record
- Accessibility
- The Accessibility Inspector exposes the page’s accessibility tree so developers can identify missing information or issues.firefox-source-docs.mozilla.org · read 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.firefox-source-docs.mozilla.org · read 12 Oct 2026
- Additional tools
- Built-in tools include Memory, Storage Inspector, Style Editor, screenshot, rulers, and JavaScript tracing features.firefox-source-docs.mozilla.org · read 12 Oct 2026
- AI integration
- The docs list Firefox DevTools MCP, an MCP server that enables AI assistants to automate and interact with Firefox.firefox-source-docs.mozilla.org · read 12 Oct 2026
- 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.firefox-source-docs.mozilla.org · read 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.firefox-source-docs.mozilla.org · read 12 Oct 2026
- Browser engine
- geckofirefox-source-docs.mozilla.org · read 21 Sep 2026
- Configuration
- Developer Tools can be docked at the bottom or side of the browser window or opened in a separate window.firefox-source-docs.mozilla.org · read 12 Oct 2026
- Developer audience
- Firefox Developer Edition is described as a browser made for developers and includes developer tools in beta.mozilla.org · read 12 Oct 2026
- Extension support
- The documentation describes extending Firefox DevTools through browser extensions.firefox-source-docs.mozilla.org · read 12 Oct 2026
- JavaScript debugger
- The JavaScript Debugger lets users step through code and examine or modify its state to track down bugs.firefox-source-docs.mozilla.org · read 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.firefox-source-docs.mozilla.org · read 12 Oct 2026
- Maker
- Mozilla says Mozilla Corporation makes Firefox and was established in August 2005 as a wholly owned taxable subsidiary of Mozilla Foundation.mozilla.org · read 12 Oct 2026
- Network Monitor
- The Network Monitor displays HTTP requests, their durations, and request details.firefox-source-docs.mozilla.org · read 12 Oct 2026
- Open source
- Yesfirefox-source-docs.mozilla.org · read 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.firefox-source-docs.mozilla.org · read 12 Oct 2026
- Purpose
- Firefox Developer Tools are built into Firefox and let web developers examine, edit, and debug HTML, CSS, and JavaScript.firefox-source-docs.mozilla.org · read 12 Oct 2026
- Remote debugging
- DevTools can connect to targets in other browsers or devices, including Firefox for Android.firefox-source-docs.mozilla.org · read 12 Oct 2026
