Is there a way that I can save all HTTP and HTTPS browser communications (including request, response, full headers and body) to files on my computer?
The HTTPS communications must be saved decrypted.
Ideally I'd be looking for something like an extension for Firefox or Google Chrome.
It must work on Linux.
Best Answer
HAR is HTTP Archive, and is exactly what you want to save (it includes HTTPS unencrypted).
Luckily this is now a basic feature of all major browser (it was not when you asked the question). No more need of third party extensions.
In Firefox (v41+):
Other browser:
In recent version of all browser, you can save HAR easily:
https://toolbox.googleapps.com/apps/har_analyzer/