Compare Code Side by Side Online

See exactly what changed between two revisions of your code. Word-level highlighting pinpoints the characters that differ, syntax highlighting covers a dozen-plus languages, and ignore-whitespace skips cosmetic reformatting.

Diff

Text Diff Checker

LOCAL · Browser-Only

Compare two texts and see the differences highlighted

Original Text

0 lines · 0 chars

Modified Text

0 lines · 0 chars

Ignore whitespaceIgnore caseIgnore line endings

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Quick Start

1Paste the original code into the left panel
2Paste the updated code into the right panel
3Pick a language for syntax highlighting (or let it auto-detect)
4Review additions in green and removals in red side by side

What This Tool Does

Side by side is the view to pick for code, because a function that moved is easier to see in two columns than in one interleaved list. Line numbers for both revisions run down the middle, so you can find the same line again in your editor.

Syntax highlighting covers eighteen options: JavaScript, TypeScript, Python, HTML, CSS, JSON, SQL, Markdown, XML, YAML, Go, Rust, Java, C and C++, PHP, Ruby, Shell, or none at all. The language is guessed from the content on the first comparison and stays where you put it once you choose one yourself.

Ignore whitespace is the setting that matters most on code. A file that has been reindented, or had its trailing spaces cleaned up, otherwise reports every touched line as a change and buries the two lines you were actually looking for.

Limits Worth Knowing

Syntax coloring and word-level highlighting do not appear on the same line at once. A line with word-level changes shows those instead of the coloring.
The comparison is textual. It does not understand your language, so a renamed variable reads as a change on every line it appears on.
Comparing very large files drops the fine alignment and shows one removed block followed by one added block.
Swap flips the two sides, which is what you want when you pasted the newer revision on the left by mistake.
A share link encodes the comparison into the URL and refuses when the content is too large to fit in one.

Common Questions

Does it understand my language?

Only for coloring. The comparison itself is line and word based, so a refactor that moves a block reads as a deletion in one place and an addition in another.

Which languages get highlighting?

Eighteen options, from JavaScript and TypeScript through Python, Go, Rust, Java, C and C++, PHP, Ruby and Shell, plus data formats like JSON, YAML and XML.

Can I download the diff?

Yes, as a .patch file, which is the format you want when the next step is applying the change rather than reading it.

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Looking for FAQs and advanced options? Visit the full Text Diff Checker page →

What This Tool Does

Limits Worth Knowing

Syntax coloring and word-level highlighting do not appear on the same line at once. A line with word-level changes shows those instead of the coloring.

The comparison is textual. It does not understand your language, so a renamed variable reads as a change on every line it appears on.

Comparing very large files drops the fine alignment and shows one removed block followed by one added block.

Swap flips the two sides, which is what you want when you pasted the newer revision on the left by mistake.

A share link encodes the comparison into the URL and refuses when the content is too large to fit in one.