Kamran Ahmed
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.
Browse project files
Run diffity tree to open a full file tree browser — no diff required. Browse your repo, read files with syntax highlighting, and leave comments on any file or folder.
diffity tree
The tree view supports the same commenting and resolve workflow as the diff viewer. Leave comments on specific lines, files, or folders, then have your agent resolve them.
/diffity-tree
Opens the file tree browser:
/diffity-tree
/diffity-resolve-tree
Reads open comments from the tree browser and makes the requested code changes:
/diffity-resolve-tree # resolve all open comments
/diffity-resolve-tree abc123 # resolve a specific thread by ID
Guided code tours
Create narrated, step-by-step walkthroughs of your codebase. Tours open in the browser with a sidebar showing the narrative and highlighted code sections.
/diffity-tour
Your agent researches the codebase, then builds a tour with highlighted code regions and rich markdown explanations:
/diffity-tour how does authentication work?
/diffity-tour explain the request lifecycle
/diffity-tour how are comments stored and retrieved?
Each tour has an intro (step 0) with an architectural overview, followed by numbered steps that highlight specific code regions and explain them in detail. The agent follows the actual execution path, not file order.
Tour steps can include sub-highlights — clickable focus links in the narrative that narrow the highlight to a specific sub-range within the step. Useful for walking through large functions section by section.
GitHub PRs
Pass a GitHub PR URL to view and review pull requests locally:
diffity https://github.com/owner/repo/pull/123
This checks out the PR, opens the diff against its base branch, and lets you leave comments in the viewer. Requires the gh CLI installed and authenticated (gh auth login), and the current repo must match the PR's repository.
You can push your comments (including AI review comments) back to GitHub as PR review comments, and pull existing GitHub comments into the viewer. Both are available from the viewer UI.
The skills work with PR URLs too:
/diffity-diff https://github.com/owner/repo/pull/123
/diffity-review https://github.com/owner/repo/pull/123
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