You can finally control serial devices from Firefox
(2026/04/14)
- Reference: 1776198080
- News link: https://www.theregister.co.uk/2026/04/14/firefox_nightly_web_serial/
- Source link:
Firefox will soon be able to communicate directly with your 3D printer. Thirteen years after the idea was initially proposed, the Web Serial API has landed in Firefox Nightly, Mozilla's work-in-progress channel for its browser.
[1]Web Serial allows browsers to interact with devices that communicate via serial ports, such as 3D printers, microcontrollers like Arduino and ESP32, and related services like smart home dashboard [2]ESPHome . It can also communicate with devices capable of emulating a serial port over USB or Bluetooth.
Google Chrome has offered [3]Web Serial support since 2021, eight years after [4]initial discussions got underway. The API is also supported on Chromium-based browsers like Edge, Opera, and Vivaldi.
[5]
Firefox Nightly 151.0a1 appears to have added Web Serial support [6]around April 13 , though there's no official documentation yet. Activating it requires setting the flag via the menu.
[7]
[8]
Six years ago, Mozilla opposed Web Serial as unsafe.
"We don't believe that user consent is adequate protection for anything that provides this level of capability," [9]wrote Martin Thomson, distinguished engineer at Mozilla, in a GitHub issues discussion back in 2020.
[10]
"Serial access is a relic from an age where a physical connection conferred a great deal of trust. For instance, many devices offer administrative control to anything that connects over this interface without any form of authentication; in my experience, this often extends to privileges that transcend even what a root user can do."
Two years later, not long after [11]a fierce forum fight on the subject, Mozilla was [12]asked to reconsider its position and Firefox CTO Bobby Holley responded positively.
[13]Claude is getting worse, according to Claude
[14]California ghost-gun bill wants 3D printers to play cop, EFF says
[15]IBM becomes first company to pay up under Trump administration's diversity blitz
[16]Man suspected of Molotov attack on Sam Altman's home charged with attempted murder
By 2024, Holley [17]said that Mozilla was "open to shipping WebSerial using the same add-on-gating mechanism as WebMIDI, provided we can come up with sufficiently understandable consent copy."
Mozilla hasn't entirely thrown caution to the wind – it still opposes [18]WebUSB (for [19]various USB devices ) and [20]WebHID (for keyboards, mice, video devices). But its wariness shifts risk from the user to the company – if there's sufficient demand to interact with devices through these APIs, lack of support will drive people away from Firefox toward the Chrome ecosystem.
And Mozilla isn't alone in its reticence. Apple's WebKit team opposes [21]Web Serial , [22]WebUSB , and [23]WebHID " [24]due to fingerprinting, security, and other concerns ," and [25]cites Mozilla's arguments about privacy and security in defense of its position.
[26]
But in 2026, with people exposing their computers to AI agents and Mozilla [27]exploring AI integration in Firefox, perhaps the worries about Web Serial look less significant in the grand scheme of things.
The [28]initial commit of Web Serial code in Firefox landed in mid-January and further work can be expected as bugs get ironed out. ®
Get our [29]Tech Resources
[1] https://developer.mozilla.org/en-US/docs/Web/API/Web_Serial_API
[2] https://web.esphome.io/
[3] https://developer.chrome.com/blog/new-in-chrome-89#hardware
[4] https://groups.google.com/g/mozilla.dev.webapi/c/wykkibp6BKo
[5] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2ad65AgBGbh4UptlhzajmHgAAA0s&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0
[6] https://www.linkedin.com/posts/schoutsen_webserial-has-landed-in-firefox-nightly-activity-7449502941868208128-zWOw?utm_source=share&utm_medium=member_desktop&rcm=ACoAAAAEUrwBGDapdyAWPL2MZIjljoJFUQRWVlo
[7] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44ad65AgBGbh4UptlhzajmHgAAA0s&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[8] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33ad65AgBGbh4UptlhzajmHgAAA0s&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[9] https://github.com/mozilla/standards-positions/issues/336#issuecomment-627050473
[10] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44ad65AgBGbh4UptlhzajmHgAAA0s&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[11] https://github.com/mozilla/standards-positions/issues/336
[12] https://github.com/mozilla/standards-positions/issues/687#issue-1363624051
[13] https://www.theregister.com/2026/04/13/claude_outage_quality_complaints/
[14] https://www.theregister.com/2026/04/14/eff_california_3dprinted_firearms/
[15] https://www.theregister.com/2026/04/14/ibm_dei_settlement/
[16] https://www.theregister.com/2026/04/14/altman_attempted_murder/
[17] https://github.com/mozilla/standards-positions/issues/687#issuecomment-1879160383
[18] https://mozilla.github.io/standards-positions/#webusb
[19] https://github.com/webusb/awesome
[20] https://mozilla.github.io/standards-positions/#webhid
[21] https://github.com/WebKit/standards-positions/issues/199
[22] https://github.com/WebKit/standards-positions/issues/68
[23] https://github.com/WebKit/standards-positions/issues/510
[24] https://webkit.org/tracking-prevention/#anti-fingerprinting
[25] https://github.com/WebKit/standards-positions/issues/68#issuecomment-1272751226
[26] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33ad65AgBGbh4UptlhzajmHgAAA0s&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[27] https://github.com/mozilla-ai
[28] https://bugzilla.mozilla.org/show_bug.cgi?id=2010930
[29] https://whitepapers.theregister.com/
[1]Web Serial allows browsers to interact with devices that communicate via serial ports, such as 3D printers, microcontrollers like Arduino and ESP32, and related services like smart home dashboard [2]ESPHome . It can also communicate with devices capable of emulating a serial port over USB or Bluetooth.
Google Chrome has offered [3]Web Serial support since 2021, eight years after [4]initial discussions got underway. The API is also supported on Chromium-based browsers like Edge, Opera, and Vivaldi.
[5]
Firefox Nightly 151.0a1 appears to have added Web Serial support [6]around April 13 , though there's no official documentation yet. Activating it requires setting the flag via the menu.
[7]
[8]
Six years ago, Mozilla opposed Web Serial as unsafe.
"We don't believe that user consent is adequate protection for anything that provides this level of capability," [9]wrote Martin Thomson, distinguished engineer at Mozilla, in a GitHub issues discussion back in 2020.
[10]
"Serial access is a relic from an age where a physical connection conferred a great deal of trust. For instance, many devices offer administrative control to anything that connects over this interface without any form of authentication; in my experience, this often extends to privileges that transcend even what a root user can do."
Two years later, not long after [11]a fierce forum fight on the subject, Mozilla was [12]asked to reconsider its position and Firefox CTO Bobby Holley responded positively.
[13]Claude is getting worse, according to Claude
[14]California ghost-gun bill wants 3D printers to play cop, EFF says
[15]IBM becomes first company to pay up under Trump administration's diversity blitz
[16]Man suspected of Molotov attack on Sam Altman's home charged with attempted murder
By 2024, Holley [17]said that Mozilla was "open to shipping WebSerial using the same add-on-gating mechanism as WebMIDI, provided we can come up with sufficiently understandable consent copy."
Mozilla hasn't entirely thrown caution to the wind – it still opposes [18]WebUSB (for [19]various USB devices ) and [20]WebHID (for keyboards, mice, video devices). But its wariness shifts risk from the user to the company – if there's sufficient demand to interact with devices through these APIs, lack of support will drive people away from Firefox toward the Chrome ecosystem.
And Mozilla isn't alone in its reticence. Apple's WebKit team opposes [21]Web Serial , [22]WebUSB , and [23]WebHID " [24]due to fingerprinting, security, and other concerns ," and [25]cites Mozilla's arguments about privacy and security in defense of its position.
[26]
But in 2026, with people exposing their computers to AI agents and Mozilla [27]exploring AI integration in Firefox, perhaps the worries about Web Serial look less significant in the grand scheme of things.
The [28]initial commit of Web Serial code in Firefox landed in mid-January and further work can be expected as bugs get ironed out. ®
Get our [29]Tech Resources
[1] https://developer.mozilla.org/en-US/docs/Web/API/Web_Serial_API
[2] https://web.esphome.io/
[3] https://developer.chrome.com/blog/new-in-chrome-89#hardware
[4] https://groups.google.com/g/mozilla.dev.webapi/c/wykkibp6BKo
[5] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2ad65AgBGbh4UptlhzajmHgAAA0s&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0
[6] https://www.linkedin.com/posts/schoutsen_webserial-has-landed-in-firefox-nightly-activity-7449502941868208128-zWOw?utm_source=share&utm_medium=member_desktop&rcm=ACoAAAAEUrwBGDapdyAWPL2MZIjljoJFUQRWVlo
[7] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44ad65AgBGbh4UptlhzajmHgAAA0s&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[8] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33ad65AgBGbh4UptlhzajmHgAAA0s&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[9] https://github.com/mozilla/standards-positions/issues/336#issuecomment-627050473
[10] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44ad65AgBGbh4UptlhzajmHgAAA0s&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[11] https://github.com/mozilla/standards-positions/issues/336
[12] https://github.com/mozilla/standards-positions/issues/687#issue-1363624051
[13] https://www.theregister.com/2026/04/13/claude_outage_quality_complaints/
[14] https://www.theregister.com/2026/04/14/eff_california_3dprinted_firearms/
[15] https://www.theregister.com/2026/04/14/ibm_dei_settlement/
[16] https://www.theregister.com/2026/04/14/altman_attempted_murder/
[17] https://github.com/mozilla/standards-positions/issues/687#issuecomment-1879160383
[18] https://mozilla.github.io/standards-positions/#webusb
[19] https://github.com/webusb/awesome
[20] https://mozilla.github.io/standards-positions/#webhid
[21] https://github.com/WebKit/standards-positions/issues/199
[22] https://github.com/WebKit/standards-positions/issues/68
[23] https://github.com/WebKit/standards-positions/issues/510
[24] https://webkit.org/tracking-prevention/#anti-fingerprinting
[25] https://github.com/WebKit/standards-positions/issues/68#issuecomment-1272751226
[26] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_software/oses&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33ad65AgBGbh4UptlhzajmHgAAA0s&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[27] https://github.com/mozilla-ai
[28] https://bugzilla.mozilla.org/show_bug.cgi?id=2010930
[29] https://whitepapers.theregister.com/
Paul Herber
If you do sell any then please wait for Request To Send to be set before posting.
Headley_Grange
Based on experience I'll get the straight and crossovers mixed up and they won't go anywhere.
David 132
These serial-related puns are good, but I'm starting to get baud.
Paul Herber
"I'll get the straight and crossovers mixed up"
You've got to be very careful of that in some jurisdictions. Loopback can get you a hefty jail sentence ...
Paul Herber
P.S. is the loft at the top of the stairway?
X-OFF
Fruit and Nutcase
Use an arduino to send X-OFF through a serial interface, to twitter/x
I know this one!
Androgynous Cupboard
I used this API very successfully to create a UI to control an industrial lighting controller I designed a few years back - super useful being able to represent the internal state with graphs and controls in HTML, and it made updates a breeze as I could flash it from the web-page too.
The UI only worked in Chrome as a Chrome app, and Google (inevitably) pulled the rug out from that a few years later, necessitating a complex workaround. Great to see it in Firefox - it’s pretty useful.
Does this mean that box of random D-types I've got in the loft will be worth selling on eBay?