When I helped to take Zulip open-source in 2015, I wrote a simple script that scrubbed secrets from the commit history using git fast-export and git fast-import

When I helped to take Zulip open-source in 2015, I wrote a simple script that scrubbed secrets from the commit history using git fast-export and git fast-import. We replaced all our secrets with xxxxxxx placeholders, replaced internal customer references with dummy names, deleted and renamed certain files, and even did some code replacements that caused certain commit diffs to become empty so those commits could be removed from the history. https://github.com/zulip/zulip/blob/3.3/tools/zanitizer https://github.com/zulip/zulip/blob/3.3/tools/zanitizer https://github.com/zulip/zulip/blob/3.3/tools/zanitizer_config.pm.sample https://github.com/zulip/zulip/blob/3.3/tools/zanitizer_conf... The script was really fast (all ~10000 commits in a few minutes), which allowed us to iterate quickly on its configuration as we audited using gitk and other tools for remaining items to scrub. Doing this work allowed us to release with an essentially complete history going back to the first commit in 2012, which has been a really valuable resource for understanding why various Zulip subsystems were written the way they were. Nowadays there are other tools for scrubbing history that might be more polished, like BFG: https://rtyley.github.io/bfg-repo-cleaner/ https://rtyley.github.io/bfg-repo-cleaner/