What is the Compare Text tool?

The Compare Text tool is a free online utility that finds the differences between two pieces of text. Paste your original on the left, the updated version on the right, and the changed lines are highlighted side by side — no setup, no account.

It uses a line-aware diff with synchronized scrolling, so matching lines stay aligned as you read. Inline word-level changes within a modified line are highlighted in color, and the gutter shows where additions, deletions, and edits occurred.

Everything runs in your browser — your text never leaves your computer. Use it for proofreading essays, reviewing code snippets, comparing config files, or auditing document revisions.

How to Use the Compare Text Tool

Three steps. The tool re-runs the diff automatically as you type, so there's no "compare" button to press.

Paste or Upload Your Original Text

Drop the original version into the left panel. You can paste directly, or click Upload to load a .txt or .md file from your computer.

Paste or Upload the Changed Text

Drop the updated version into the right panel. As soon as both panels have content, the diff appears with deletions on the left and insertions on the right, lined up by row.

Review, Copy, or Download

Use Clear to reset a panel, Swap to flip the two sides, or Copy / Download to save either text. Scroll either side — both panels stay in sync.

When You'd Actually Use This

Proofreading & Editing

Compare an earlier draft with your latest revision and instantly see every word, sentence, and paragraph that changed. Great for essays, reports, contracts, and emails.

Code Review

Paste two versions of a function or config snippet to spot tweaks at a glance — handy when you don't want to spin up a full diff tool or git client just to check a few lines.

Document Versioning

Compare two revisions of a policy, spec, or readme. Track exactly which paragraphs changed between V1 and V2 without combing through the full document.

Translation Checks

Paste an original text and a corrected translation side by side to see exactly what the editor changed — useful for learning patterns and improving future translations.

Common Questions

Is my text stored anywhere?

No. The diff runs entirely in your browser using JavaScript. Nothing is uploaded or saved on a server.

How big can the texts be?

Performance depends on your device. Small and medium texts diff instantly. For very large texts (hundreds of KB or more) the diff may take a moment, but it still runs locally.

What kind of differences does it detect?

Line-by-line differences with inline word-level highlighting inside changed lines. Insertions, deletions, and modifications are color-coded.

Can I upload files?

Yes. Click Upload on either panel to load a plain-text file. The contents replace whatever is currently in that panel.

Does it work offline?

Once the page is loaded, the comparison runs locally — so an unstable connection doesn't affect it. The page itself still needs an initial load over the network.

Why do the two panels scroll together?

Synchronized scrolling keeps matching lines aligned across both sides. Scroll either one and the other follows so changed regions stay easy to compare.

Other Tools You Might Need

Comparing text is one of many tasks. More tools are on the way — bookmark this page and check back.