I used WebSerial + WebSockets during hardware to prototype some connected hardware (on boards that didn’t have WiFi).
Plug in to USB, fire up the web app, and then press a button in NY to light up LEDs in SF – it was exciting stuff!
I never tried actually programming the boards over WebSerial; that obviously opens up many more use cases. I’m thinking about the success that p5.js has had in the creative coding community, largely driven (I think) by a low barrier to entry since it just requires a web browser to get started.
WebSerial was just introduced in Firefox 151. It was already available for 5 years in Chromium based browser. It's so new in Firefox that even caniuse is not up-to-date: https://caniuse.com/web-serial.
It would not be quite as seamless as having serial support included out of the box in the browser, but couldn't you get most of the way there by writing a native application that provides provides a network interface to the serial ports and then a JavaScript library for use in the browser than talks to that application over the network (maybe even making the JavaScript library API match the Web Serial API so code written for Chromium's actual Web Serial requires little of no porting)?
The native apps for Linux, Windows, and MacOS would be pretty simple, and would be independent of browser vendor or version.
This might even allow some flexibility that serial implemented in the browser doesn't have, such as allowing control of serial ports on a different host.
I'd have expected that when people saw that Web Serial in Chromium opened up some great possibilities for things like browser based Arduino development but other browser makers were not on board someone would had thoughts similar to what I've described.
Does this exist and I just missed it? Is there some major difficulty I've overlooked?
That's a start at improving something. But it won't rid itself of the Playskool/Fisher-Price gimmick factor or have any lasting effect until we can convince JS developers to write their own tools in a standards-compliant dialect and use standardized APIs so that contributors can use the runtime they already have installed instead of being cajoled and browbeaten into installing NodeJS or Bun or Deno or whatever to do what the browser runtime is perfectly capable of: opening a project directory, executing the code comprising the build script, and outputting the build artifacts when it's done.
> do what the browser runtime is perfectly capable of: opening a project directory, executing the code comprising the build script, and outputting the build artifacts when it's done
Unfortunately Firefox doesn't support the FileSystem API so to do this you need to resort to uploading the entire source code directory each time you change a source file.
I understand Firefox's privacy and security first thinking on this, but I think it is misguided. It's led to the webplatform being eclipsed by other, propriety options, or people forced to ship "Chrome-based only" features.
Great to see Firefox getting on board. I wrote an alternative to Arduino's serial plotter that works in Chrome. Hopefully it's not too hard to get Firefox working too? Patches welcome:
Using serial comms from the browser is really important in educational robotics programs. Both First and Vex platforms support it. Kids can access the web based coding environment on their chromebooks, and send code to the robots with a usb cable.
We recently restarted our middle school robotics club. The school had a lot of old Vex EDR equipment for which the coding software is windows only so that really limited what we could do related to coding. Glad to see Firefox getting up to speed on this.
I don't mean enabling them in `about:config`. The actual pages you visit must request access these features from the user, including selecting which device(s) it is allowed to access. So even if Firefox enabled all of these APIs by default nothing will be able to access your devices without your permission.
It's handy for situations where you have inexperienced people needing to flash microcontrollers. Meshtastic is a great example, it's meant for a wide variety of users from people that can actually write code to people that have only maybe heard of a raspberry pi in passing. You buy a transceiver on Amazon, go to the meshtastic website, plug in the transceiver, and hit "flash". Also, I don't want to have to download yet another custom Arduino IDE. I don't need to actually modify the running code, I just want the binary on the device so I can move on with playing with it.
Mozilla's response to "Request for Mozilla Position on an Emerging Web Specification", June 2020:
> For raw device access as envisioned in a number of APIs (Web USB, Web Bluetooth, Web NFC, and Web MIDI), the risks of exposing those APIs to users cannot be reasonably conveyed. This is pretty much an intractable flaw of allowing raw, non-semantic access to devices regardless of the protocol used to do so.
> The specific issue is: it's not intuitive that allowing malicious-site.com to access your Bluetooth keyboard might give that site access to your stored passwords, give them the ability to hijack your DNS settings, or allow them to encrypt your hard drive and hold it ransom. And if it's not immediately obvious how those things are possible, that only serves to demonstrate how completely non-intuitive the risks are and how intractable trying to explain them in a permission prompt would be.
Feels a bit out of place that the website tries to aggressively make me download Firefox, with multiple links on the site for it. Like it's the 2000's again and I'd need ActiveX or something. But it's to use a standard.
Sure, the standard is cool, have used it to flash Meshtastic to some LoRa boards, before advancing to use VS Code + ESP-IDF to flash in my own LoRa code.
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[ 5.0 ms ] story [ 46.3 ms ] threadPlug in to USB, fire up the web app, and then press a button in NY to light up LEDs in SF – it was exciting stuff!
I never tried actually programming the boards over WebSerial; that obviously opens up many more use cases. I’m thinking about the success that p5.js has had in the creative coding community, largely driven (I think) by a low barrier to entry since it just requires a web browser to get started.
It would not be quite as seamless as having serial support included out of the box in the browser, but couldn't you get most of the way there by writing a native application that provides provides a network interface to the serial ports and then a JavaScript library for use in the browser than talks to that application over the network (maybe even making the JavaScript library API match the Web Serial API so code written for Chromium's actual Web Serial requires little of no porting)?
The native apps for Linux, Windows, and MacOS would be pretty simple, and would be independent of browser vendor or version.
This might even allow some flexibility that serial implemented in the browser doesn't have, such as allowing control of serial ports on a different host.
I'd have expected that when people saw that Web Serial in Chromium opened up some great possibilities for things like browser based Arduino development but other browser makers were not on board someone would had thoughts similar to what I've described.
Does this exist and I just missed it? Is there some major difficulty I've overlooked?
Unfortunately Firefox doesn't support the FileSystem API so to do this you need to resort to uploading the entire source code directory each time you change a source file.
I understand Firefox's privacy and security first thinking on this, but I think it is misguided. It's led to the webplatform being eclipsed by other, propriety options, or people forced to ship "Chrome-based only" features.
https://github.com/skybrian/serialviz
We recently restarted our middle school robotics club. The school had a lot of old Vex EDR equipment for which the coding software is windows only so that really limited what we could do related to coding. Glad to see Firefox getting up to speed on this.
And maybe we'll get web bluetooth too.
I've always agreed with the reservations about browsers being able to control peripherals. I'd rather download a python script i can inspect.
https://hacks.mozilla.org/2026/05/web-serial-support-in-fire...
and the CIA
> needing to flash microcontrollers
> For raw device access as envisioned in a number of APIs (Web USB, Web Bluetooth, Web NFC, and Web MIDI), the risks of exposing those APIs to users cannot be reasonably conveyed. This is pretty much an intractable flaw of allowing raw, non-semantic access to devices regardless of the protocol used to do so.
> The specific issue is: it's not intuitive that allowing malicious-site.com to access your Bluetooth keyboard might give that site access to your stored passwords, give them the ability to hijack your DNS settings, or allow them to encrypt your hard drive and hold it ransom. And if it's not immediately obvious how those things are possible, that only serves to demonstrate how completely non-intuitive the risks are and how intractable trying to explain them in a permission prompt would be.
https://github.com/mozilla/standards-positions/issues/95#iss...
Sure, the standard is cool, have used it to flash Meshtastic to some LoRa boards, before advancing to use VS Code + ESP-IDF to flash in my own LoRa code.