How to monitor websocket frames in firefox

Question

I know there was an extension called 'websocket-monitor', but it's no longer available.

It seems that nobody can view websocket frames by firefox.

Answer 1

That is currently not possible with the latest version of Firefox, but it has been logged and there is an open thread in Bugzilla regarding it here.

Update September 2019: According to this tweet from Mozilla, the WebSocket inspection is now working natively on the Firefox Developer edition.

Update October 2019: According to this extensive blog post from Mozilla, the feature will be released in Firefox 71. Until that, you can use Firefox Developer edition.

Update December 2019: Firefox 71 got released today and includes WebSocket inspection according to the release notes.

You can download the Firefox Developer edition from here.

Update October 2020: Sometime between Firefox 71 and Firefox 79 the "Messages" tab was removed and instead the WebSocket messages inspection was moved to the standard "Response" tab.

Answer 2

It's now possible to view/sniff WebSocket messages/frames/packets with the Nightly build of Firefox. I have never used the Firefox Nightly build before, but it seems to be working okay.

Here's a screenshot: