diffstitch

Compare multiple git branches against a base in a side-by-side HTML diff view.

diffstitch generates a self-contained HTML report that lets you compare several feature branches against a common base at once. The left panel always shows the base branch; the right panel shows the selected branch's changes and includes a dropdown to switch between branches on the fly.

gem install diffstitch

Or add it to your Gemfile:

gem 'diffstitch'

diffstitch <base> <branch1> [branch2 ...] [options]

Compare two feature branches against main:

diffstitch main feature-auth feature-payments

Open in the browser immediately:

diffstitch main feature-auth --open

Custom output location and title:

diffstitch main feature-a feature-b feature-c \
  --output ./reports/sprint-42 \
  --title "Sprint 42 branch review"

diffstitch writes four files to the output directory — open index.html in any browser:

Diff rendering uses diff2html loaded from jsDelivr.

git clone https://github.com/sroomberg/diffstitch
cd diffstitch
bundle install
bundle exec rspec        # run tests
bundle exec rake         # same, via default Rake task

bin/diffstitch                  # executable entry point
lib/
  diffstitch.rb                 # top-level require
  diffstitch/
    version.rb                  # VERSION constant
    git.rb                      # Git module (in_repo?, verify_ref!, diff)
    generator.rb                # writes output directory
    cli.rb                      # OptionParser + orchestration
    assets/
      index.html.erb            # ERB template
      styles.css                # diff2html overrides and scrollbar
      app.js                    # browser-side rendering and sync scroll
      bootstrap.min.css         # Bootstrap 5.3.3 (bundled)
spec/
  diffstitch/
    git_spec.rb
    generator_spec.rb
    cli_spec.rb

1. Update CHANGELOG.md — add a ## [x.y.z] - YYYY-MM-DD section.
2. Bump VERSION in lib/diffstitch/version.rb.
3. Commit and push.
4. Tag and push the tag:

   git tag v0.1.0
   git push origin v0.1.0

   The Release workflow will run CI and, if it passes, create a GitHub Release using the CHANGELOG entry for that version.

See CHANGELOG.md.

MIT