Diffity is an agent-agnostic, GitHub-style diff viewer and code review tool.
npm install -g diffityIt works with Claude Code, Cursor, Codex, and any AI coding agent.
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 commitsThe --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.
Install the skills for your coding agent (Claude Code, Cursor, Codex, etc.):
npx skills add kamranahmedse/diffityThen use the slash commands:
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.
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
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.
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 && diffityIf 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--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