Firefox WebSerial support

[dhalbert]

Firefox as of version 151 now supports WebSerial (https://hacks.mozilla.org/2026/05/web-serial-support-in-firefox/), would circuitpy.dev be able to work on Firefox? RIght now it asks for a Chrome-based browser. I tested on Firefox 152.0.4.

[urfdvw]

Thank you for your feedback. Actually, in this latest version, I tested Firefox locally, but it turns out that file system APIs are not very available on Firefox yet.

This project now relies on the file system API to open CircuitPy directory. I know Adafruit's Web Editor is supporting Firefox at the moment. I can check how it works and may use similar mechanisms to support Firefox in this project in the next version.

[dhalbert]

https://github.com/circuitpython/web-editor now supports Firefox when CIRCUITPY is writable, so on boards without USB MSC, like ESP32.

We have been discussing how to get around the read-only issue here: circuitpython/web-editor#399.

I don't think Firefox is going to do a filesystem Web API soon. In the past they were negative about it for security reasons.

EDIT: I opened adafruit/circuitpython#11091 to relocate some discussion in circuitpython/web-editor#399 to the circuitpython repo.

[urfdvw]

I think the discussion threads you mentioned are very interesting, and I can also do some research on my side to see what the options are.

Either way, a serial-based file system seems to be very valuable to support. I can go down that path and at least try to support some of the microcontrollers that don't have USB mass storage.