diffity

Diffity is an agent-agnostic, GitHub-style diff viewer and code review tool.

npm install -g diffity

It works with Claude Code, Cursor, Codex, and any AI coding agent.

See your diffs

Run diffity inside any git repo — your browser opens with a GitHub-style, syntax-highlighted diff.

# everyday use
diffity                                    # review all uncommitted changes
diffity HEAD~1                             # review your last commit
diffity HEAD~3                             # review your last 3 commits

# branch workflows
diffity main                               # compare current branch against main
diffity main..feature                      # compare feature branch against main
diffity main feature                       # same as above, shorthand syntax
diffity --base main --compare feature      # same as above, explicit flags

# releases and tags
diffity v1.0.0 v2.0.0                     # compare two releases
diffity v1.0.0                             # what changed since v1.0.0

# specific commits
diffity abc1234                            # changes since a specific commit
diffity abc1234..def5678                   # changes between two commits

The --base/--compare flags use the same terminology as GitHub PRs — base is what you're comparing against, compare is the branch with changes. You can also use range syntax (main..feature) or just pass two positional args (diffity main feature).

You can leave comments on any diff — working tree changes, branch comparisons, commit ranges. Copy them into your agent with a button and ask it to resolve them, or use the skills below to let your agent auto-review and auto-solve them.

AI code review

Install the skills for your coding agent (Claude Code, Cursor, Codex, etc.):

npx skills add kamranahmedse/diffity

Then use the slash commands:

/diffity-diff

Opens the diff viewer in your browser. Accepts the same refs as the CLI, plus natural language:

/diffity-diff                          # working tree changes
/diffity-diff main                     # current branch against main
/diffity-diff main..feature            # branch diff
/diffity-diff HEAD~1                   # last commit
/diffity-diff last 3 commits           # natural language works too

Leave comments on any line — when you're done, run /diffity-resolve to have your agent fix them.

/diffity-review

Your agent reviews the diff and leaves inline comments in the viewer. Uses severity tags ([must-fix], [suggestion], [nit], [question]) so you can triage by importance. Supports refs, focus areas, and natural language:

/diffity-review                             # review working tree changes
/diffity-review main                        # review what you're merging into main
/diffity-review main..feature               # review what you're merging into main
/diffity-review identify security issues    # focus on security issues
/diffity-review performance in src/lib      # focus on performance in specific dir
/diffity-review last 3 commits              # natural language works too

/diffity-resolve

Reads all open comments and makes the requested code changes. Works with both your comments and AI review comments:

/diffity-resolve                       # resolve all open comments
/diffity-resolve abc123                # resolve a specific thread by ID

A typical workflow: run /diffity-review to get AI feedback, check the comments in the browser, then run /diffity-resolve to apply the fixes.

Multiple projects

Diffity supports running multiple projects simultaneously. Each gets its own port automatically:

# Terminal 1 — starts on :5391
cd ~/projects/app && diffity

# Terminal 2 — starts on :5392
cd ~/projects/api && diffity

If you run diffity in a repo that already has a running instance, it opens the existing one instead of starting a new server. Use --new to kill the existing instance and start fresh.

diffity list               # show all running instances
diffity list --json        # machine-readable output

Options

--base <ref>       Base ref to compare from (e.g. main, HEAD~3, v1.0.0)
--compare <ref>    Ref to compare against base (default: working tree)
--port <port>      Custom port (default: auto-assigned from 5391)
--no-open          Don't open browser
--dark             Dark mode
--unified          Unified view (default: split)
--quiet            Minimal terminal output
--new              Stop existing instance and start fresh

License

PolyForm Shield 1.0.0 © Kamran Ahmed