The diff checker that shows you exactly what changed
Most free diff checker tools online show you which lines changed. That's useful, but it's only half the picture. If a line says "The quick brown fox jumps over the lazy dog" and it was changed to "The quick brown fox leaps over the lazy cat", a line-level diff tells you the line is different. A word-level diff shows you that "jumps" became "leaps" and "dog" became "cat" — the two specific words that actually changed.
Our tool does word-level comparison. Within any changed line, the specific words that were added or removed are highlighted separately, so you can see the precise change without manually reading and comparing the two versions character by character.
Two view modes — unified and split
Unified view
The unified view shows a single column of output. Unchanged lines appear in grey. Removed lines (from text A) appear in red with a minus sign. Added lines (from text B) appear in green with a plus sign. This is the same format used by the Unix diff command and by Git's diff output — it's compact and easy to read for long documents.
Split view
The split view shows text A on the left and text B on the right, side by side. Corresponding lines appear at the same vertical position, so you can scan across and see exactly what a line looked like before and after. This is the mode most people find intuitive when comparing shorter blocks of text or when you want to read both versions simultaneously.
Ignore whitespace — when spaces don't matter
The "Ignore whitespace" option strips leading and trailing spaces from each line before comparing, and collapses internal whitespace sequences to a single space. This is useful when comparing code that may have been reformatted, or text that was copied from different sources with inconsistent indentation. Without this option, "Hello World" and "Hello World" would be flagged as different. With it, they're treated as identical.
What the stats bar tells you
After running a comparison, the stats bar shows four numbers:
- Lines added — lines that exist in text B but not in text A.
- Lines removed — lines that exist in text A but not in text B.
- Lines changed — lines that exist in both versions but with different content.
- Unchanged — lines that are identical in both versions.
These four numbers give you a quick sense of how different the two texts are before you read through the detailed output. A document with 200 unchanged lines and 3 changed lines is very close to its original. A document with 50 removed and 60 added is substantially rewritten.
When do you need a diff checker?
Comparing document drafts
If you've received a revised version of a document and want to know exactly what the editor changed, a text compare online tool gives you a precise answer in seconds. Paste the original and the revised version, run the diff, and every change is highlighted. No manual reading and cross-referencing required.
Checking code changes
Developers use diff tools constantly to review changes before committing code. If you don't have access to a Git interface or a code editor with built-in diff functionality, this online code diff checker lets you compare two versions of a script, config file, or any code snippet directly in the browser.
Reviewing translations
Translation teams use diff tools to check what changed between source documents when updating translated content. If the source text has been updated, comparing the old and new versions reveals exactly which sentences need to be retranslated.
Verifying copy-paste accuracy
When copying text between systems — from a PDF to a Word document, from a CMS to a template, from one database to another — characters can be dropped, changed, or duplicated. Comparing the original and the copy confirms whether the transfer was accurate.
Content quality checking
SEO professionals and content teams use diff tools to verify that a page's content hasn't changed unexpectedly — for example, after a CMS update or a site migration. Comparing a saved copy with the current live version quickly reveals any unintended changes.
Frequently asked questions
No. All comparison happens in your browser using JavaScript. Your text never leaves your device. You can safely compare confidential documents, proprietary code, or any sensitive content.
Unified view shows all changes in a single column — removed lines in red, added lines in green, unchanged lines in grey — which is compact and good for long documents. Split view shows the two texts side by side with corresponding lines at the same vertical position, which makes it easier to read both versions simultaneously and compare shorter blocks of text.
For lines where the content changed (not entirely added or removed), the tool compares the individual words within the line and highlights the specific words that differ. Words present in B but not A are highlighted in bright green. Words present in A but not B are highlighted in red with strikethrough. This lets you spot exactly what changed within a line without having to read the whole line carefully.
Yes. The tool compares any plain text — code, prose, data, or anything else. The monospace font in the output makes code easier to read. For comparing JSON, use the "Ignore whitespace" option if the formatting differs between the two versions.
There's no hard limit — the tool runs entirely in your browser and processes as much text as your device can handle. Very large files (tens of thousands of lines) may take a moment to process on slower devices, but there's no server-side cap.