Firefox 151 adds Web Serial for desktop
Firefox 151 for Desktop adds Web Serial support for compatible hardware. It gives web-based device tools another browser to support. Check permissions, operating-system support and actual devices before removing a native fallback.
What changed
Firefox 151 for Desktop implements Web Serial. Mozilla describes testing hardware workflows with Adafruit and examples such as device configuration and power-meter readings.
Who it helps
Developers building firmware installers, hardware configuration pages or monitoring tools can test Firefox alongside their existing supported browsers.
What to do
Check API availability before showing a connection button. Test permission denial, disconnected devices and reconnection on supported systems. Keep a fallback for unsupported environments. The announcement concerns desktop Firefox; do not assume the same availability on phones or every other browser.
Source
Mozilla Hacks, May 2026.
Interview question
How does Firefox 151's Web Serial API allow web apps to handle hardware tasks previously requiring native installers?
- a.By including a built-in polyfill that translates Chromium Web Serial calls for Firefox
- b.By routing hardware commands through a Mozilla-signed background service
- c.By automatically enumerating all serial ports when a site loads
- d.By letting JavaScript read and write directly to USB serial devices after explicit user permissionCorrect
Why? this is the answer
Firefox 151 implements the Web Serial API natively, so JavaScript can call navigator.serial.requestPort() to access hardware directly after the user explicitly grants permission, removing the need for native binaries. Distractor A is wrong because sites cannot silently probe ports—the permission model requires an explicit grant per site and port.
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Read the original → hacks.mozilla.org
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- #web-serial
- #hardware
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