Git Diff Viewer · macOS

See exactly what changed.
Without the terminal noise.

SeamDiff is a native Mac app that turns raw git diffs into clean, readable side-by-side comparisons — with syntax highlighting, dark mode, and zero configuration.

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before
12function fetchUser(id) {
13  return db.query(id);
14}
15 
16module.exports = fetchUser;

after
12async function fetchUser(id) {
13  const user = await db.query(id);
14  return user ?? null;
15 
16module.exports = fetchUser;

Why `git diff` in the terminal falls short

The built-in git diff command is powerful — but reading walls of unified diff output in a terminal window is slow and error-prone. Lines blend together, context gets lost, and spotting a subtle logic change across 200 lines is genuinely hard.

A dedicated diff viewer solves this. You get a structured, side-by-side layout where added and removed lines sit directly opposite each other, making it immediately obvious what was swapped, rewritten, or moved — not just what the raw patch says.

Everything you need. Nothing you don't.

SeamDiff is focused on one job: showing you what changed, clearly. No plugins, no accounts, no setup — just open two files and start reading.

⇄

Side-by-side diff

Before and after sit next to each other so your eye can track every line change without scrolling back and forth.

✦

Syntax highlighting

◑

Dark & light mode

Follows your macOS system appearance automatically. Switch once in System Settings, SeamDiff follows along.

≡

Inline unified mode

Prefer the classic unified patch view? Toggle to inline mode and see additions and removals interspersed in a single column.

✎

Customizable colors

Adjust the hue and opacity of diff highlight colors to match your taste or reduce eye strain over long review sessions.

⌗

Live change stats

A footer bar shows additions, removals, and total changed lines at a glance — useful for assessing diff scope before review.

Using SeamDiff with git — three workflows

Drag and drop from Finder

Save two versions of a file from your git working tree — git show HEAD:path/to/file > old.js — then drag both onto SeamDiff. No configuration needed.

Open files with the file picker

Hit the left or right panel button, pick any file from disk. SeamDiff remembers the last folder you used on each side, so repeated reviews in the same project stay fast.

Review before committing

Compare your working copy against the last committed version to catch accidental changes before they land in version control. A second pair of eyes before every git commit.

How SeamDiff compares

There's no shortage of diff tools on macOS. Here's an honest look at how the main options stack up for day-to-day git work.

Feature	SeamDiff	git diff (CLI)	FileMerge	Kaleidoscope
Side-by-side view	✓	—	✓	✓
Syntax highlighting	✓	—	—	✓
Native macOS app	✓	✓	✓	✓
Dark mode	✓	—	—	✓
One-time purchase	✓	Free	Free	Subscription
No Xcode required	✓	—	Needs Xcode	✓
Customizable colors	✓	—	—	—

Who uses SeamDiff?

Developers who want a quick visual sanity-check before committing, or a cleaner view of a colleague's pull request diff than what GitHub renders in the browser.

Designers and writers who version-control assets, config files, or copy — and need to see exactly what line changed in a JSON or Markdown file without reading a raw patch.

Anyone on macOS who's ever squinted at a terminal window wishing the colored output were just a bit more readable. SeamDiff is that upgrade — native, fast, and built for the Mac.

Ready to see your diffs clearly?

SeamDiff is available on the Mac App Store — one-time purchase, no subscription.

Join the waitlist

See exactly what changed.Without the terminal noise.

Why git diff in the terminal falls short