Which browsers and operating systems support Let's Encrypt

Is there any place that collects information on whether LE is supported by various antivirus and MITM security vendors? I’ve encountered trouble with Avast. @mholt mentioned “multiple reports” about other Windows antivirus software in another thread

Would be useful to collect that info in addition to OS/browser support; we had to move off of letsencrypt for now because of trust issues with Avast.