Compare & Merge Text

The fastest way to see changes between two blocks of text or code.

Source Code - let theme = "light"; initApp(theme);

Modified Code + const theme = "dark"; initApp(theme);

Ctrl+Enter to compare · Ctrl+↑↓ to navigate · Ctrl+Esc to edit

⬤ Source Text

Upload

⬤ Modified Text

Upload

Why Choose DiffTools

Designed for precision and speed

Everything you need to compare, merge, and refine text — in one clean workspace.

Word, char & line diff

Switch granularity to catch every change — from single characters to full lines.

One-click merge

Accept individual changes or merge all at once — left or right.

Drag & drop files

Upload plain-text files directly into either pane — instant comparison.

Private by design

All processing runs in your browser. Never sent to any server.

Undo & redo

Made a mistake? Undo any merge or edit instantly on either side.

Keyboard shortcuts

Navigate & compare at full speed with Ctrl+Enter, Ctrl+↑↓ and more.

How it works

Three steps to a clean diff

No account, no install, no waiting. Just paste, compare, and merge.

Paste your text

Add original and modified versions to the left and right panes.

Click Compare

Instantly see additions, deletions, and modifications highlighted.

Merge & copy

Accept the changes you want and copy the final result.

Visual guide

See the diff in action

A quick example of how changes are highlighted and merged.

Text comparison visual guide showing side by side diff

Use cases

Built for every workflow

From code reviews to contract edits, the diff tool handles them all.

Code

Code reviews

Compare two versions of a script, function, or config file before merging a pull request.

Writing

Document editing

Track what changed between drafts of a report, essay, or proposal without Track Changes.

Legal

Contract versions

Spot every clause addition or deletion between two contract drafts in seconds.

Data

Config & JSON diff

Compare environment configs, JSON payloads, or CSV exports to diagnose issues fast.

SEO

Content updates

Audit exactly what copy changed on a page before and after a site update.

Translation

String comparison

Verify translation files match their source by diffing locale strings side by side.

FAQ

Frequently asked questions

Everything you need to know about the text comparison tool.

Is my text kept private?

Yes, completely. All comparison logic runs inside your browser using the Myers diff algorithm. Your text never leaves your device and is never sent to any server.

What is the file size limit?

There is no hard server-side limit because processing happens locally. Very large files may be slower depending on your device, but there is no cap on input size.

What diff modes are available?

Three modes: word diff, character diff, and line diff. Switch between them instantly without re-pasting your content.

Can I compare code files?

Absolutely. The tool works with any plain-text content — JavaScript, Python, JSON, YAML, HTML, CSS, or any other code. Paste directly or drag and drop a file.

What does the merge feature do?

Each changed block shows a merge arrow. Click it to accept that change into the opposite pane. Use "All Left" or "All Right" to accept all changes at once. Undo is always available.

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