Text 🔒 Client-side only

Diff Checker

Compare two text blocks or code snippets online to instantly find the differences. 100% client-side privacy.

ORIGINAL TEXT

MODIFIED TEXT

Diff Level: Character Word Line

DIFF RESULT

Enter text in both fields to see differences...

What is an online Diff Checker?

A diff checker online is a developer utility that compares two blocks of text or code side-by-side to highlight the exact differences between them. "Diff" is short for difference. It is an essential tool for programmers tracking code changes, writers revising drafts, or anyone trying to spot subtle modifications in long documents without manually reading every line.

How to use the Diff Checker

Paste the original version of your text into the left "Original Text" input area.
Paste the updated or altered version into the right "Modified Text" input area.
Select the granularity of the comparison: "Character", "Word", or "Line" level.
Click the Compare Text → button. The unified diff result will appear below, highlighting additions in green and deletions in red.

Features

✓ 100% client-side — your code or private text never leaves the browser. Zero server uploads.
✓ No sign-up or account required. Free forever.
✓ Three comparison modes: Analyze changes down to the individual character, split by full words, or compare whole lines at a time.
✓ Unified View: See exactly what changed in a single, continuous flow. Red text indicates removals from the original; green text indicates additions in the modified version.
✓ Instantly swap the original and modified inputs with one click.

FAQ

Which diff mode should I use?

Word mode is generally best for prose and standard code, as it groups changes logically. Line mode is much faster for comparing massive log files or long code bases where you only care which rows changed. Character mode provides the most granular detail, useful for finding single-letter typos or spelling corrections.

Is my data uploaded to a server?

No. ZeroTools processes the text comparison entirely within your browser using JavaScript. No data is transmitted, ensuring absolute privacy for sensitive source code, API keys, or confidential documents.