firefox-cert-override is a Python library and CLI utility for reading and writing cert_override.txt files.
cert_override.txt is located at the root of a Firefox profile directory and stores the per-domain certificate overrides for that profile. When you permanently add an exception for Firefox to trust a certificate for a specific domain, Firefox adds an entry to cert_override.txt, and will read it on startup in the future to load the override again.
firefox-cert-override requires (read: has only been tested on) Python 3.5.
$ pip install firefox-cert-override
There isn't any documentation for the API (yet), but firefox_cert_override/base.py is where the main functionality lives and is a quick skim.
The package adds a firefox-cert-override command that takes a list of domain and certificate file path pairs and outputs the contents for a cert_override.txt file with overrides for the given domains. See firefox-cert-override --help for more details.
Licensed under the MIT License. See LICENSE for details.