Mozilla has added support for the Web Serial API in Firefox on the desktop with the release of Firefox 151. The API allows the browser to communicate directly with hardware devices such as microcontrollers, development boards, and other serially connected equipment without the need for additional software.
This update brings Firefox closer to feature parity with Chromium-based browsers, which have supported Web Serial for several years. Mozilla believes this change is primarily useful for developers, creators, educators, and embedded device communities, rather than the general user base.
What the Web Serial API allows in Firefox 151
Web Serial allows web pages to connect and communicate with hardware devices over a serial connection. Common uses include programming microcontrollers directly from a browser, configuring development boards via web-based tools, reading sensor data in a web application, and updating firmware on embedded devices.
Previously, many of these tasks required users to use Chrome or Chromium-based browsers, since Web Serial was not available in Gecko. However, with Firefox 151, these workflows are now possible in Firefox without additional configuration for many projects.
Collaboration with Adafruit brings browser-based hardware workflows to Firefox
Mozilla is launching the feature alongside a collaboration with Adafruit, the open source hardware community known for CircuitPython, programmable microcontrollers, and education-focused electronics kits. Adafruit’s browser-based hardware workflows, including its WebSerial ESPTool, now work directly in Firefox.
Users can experiment with projects involving CircuitPython programming, board flashing, sensor input, and microcontroller communication without leaving the browser or installing dedicated client software.
Mozilla has published a detailed engineering post on Hacks.mozilla.org for developers interested in the implementation details behind Web Serial support in Gecko.
Web Serial Availability in Firefox 151
Web Serial support is now available on Firefox 151 on desktop. Mozilla has not announced whether the API will be added to Firefox on Android or iOS, where browser engine restrictions on iOS limit how Web Serial could be implemented even if Mozilla decided to include it.
The update also includes other features in Firefox 151, such as VPN location selection, expanded language support for Shake to Resume, and a one-click private browsing reset button.
