List remote GitHub branches that are older than 1 year

list_remote_github_branches_older_than_1_year.sh

#!/bin/bash

gh api graphql --paginate -f query='
    query($owner: String!, $repo: String!, $endCursor: String) {
      repository(owner: $owner, name: $repo) {
        refs(refPrefix: "refs/heads/", first: 100, after: $endCursor, orderBy: {field: TAG_COMMIT_DATE, direction: ASC}) {
          edges {
            node {
              name
              target {
                ... on Commit {
                  committedDate
                }
              }
            }
          }
          pageInfo {
            hasNextPage
            endCursor
          }
        }
      }
    }
  ' -F owner={owner} -F repo={repo} \
    | jq --arg cutoff_date "$(date -d '1 year ago' --iso-8601=seconds)" -s \ '
        map(
            .data.repository.refs.edges
            | .[].node
            | {branch: .name, committedDate: .target.committedDate}
        )
        | flatten
        | sort_by(.committedDate)
        | .[]
        | select(.committedDate < $cutoff_date)
        '

You can use the output to cleanup some old branches.

Caution

Don't blindly run this, you might delete important branches in your GitHub repo.

... | jq .branch -r | xargs -n 1 git push --delete --dry-run origin