Anonymise Git history

git-anonymize

#!/bin/sh

# Suppose you want to do blind reviewing of code (eg for job interview
# purposes). Unfortunately, the candidates' names and email addresses are
# stored on every commit! You probably want to assess each candidate's version
# control practices, so just `rm -rf .git` throws away too much information.
# Here's what you can do instead.

# Rewrite all commits to hide the author's name and email
for branch in `ls .git/refs/heads`; do
    # We may be doing multiple rewrites, so we must force subsequent ones.
    # We're throwing away the backups anyway.
    git filter-branch -f --env-filter '
        export GIT_AUTHOR_NAME="Anonymous Candidate"
        export GIT_AUTHOR_EMAIL="[email protected]"' $branch
done

# Delete the old commits
rm -rf .git/refs/original/

# Delete remotes, which might point to the old commits
for r in `git remote`; do git remote rm $r; done

# Your old commits will now no longer show up in GitK, `git log` or `git
# reflog`, but can still be found using `git show $commit-id`.

Almost perfect! But this script doesnt anonimize commits on tags! For that you have to replace the whole for git filter-branch loop with something like https://github.com/adamdehaven/change-git-author/blob/master/changeauthor.sh#L536, that is:
git filter-branch -f --env-filter '... exports ...' --tag-name-filter cat -- --branches --tags

Now yes!

(correction script taken from https://www.adamdehaven.com/blog/update-commit-history-author-information-for-git-repository/#instructions)

To cleanup the merge commit messages, I've used:

for branch in `ls .git/refs/heads`; do
  git filter-branch -f --msg-filter 'sed "s/Merge pull request.*$/Merge pull request #xxx from anonymous_repo/g"' $branch
done

Also be aware of merge branch commits, sometimes branch names includes people usernames:

for branch in `ls .git/refs/heads`; do
  git filter-branch -f --msg-filter 'sed "s/Merge branch.*$/Merge branch anon into anon/g"' $branch
done