Text Diff Checker
Compare two blocks of text and instantly see what changed. Additions are highlighted green, removals in red.
What Is a Text Diff Checker?
A text diff checker compares two versions of a piece of text and highlights every difference between them — which lines or characters were added, removed, or changed. The term comes from the Unix diff command, which has been comparing files since the early 1970s. Diff algorithms identify the longest common subsequence between two texts and then mark everything else as an addition or deletion.
The output of a diff can be displayed in several formats: a side-by-side comparison that shows the two versions in parallel columns, an inline comparison that shows both versions sequentially with inserted and deleted text marked, or a unified patch format that lists only the changed sections with context lines. Our tool highlights changes at the character level for maximum precision.
When to Compare Text
Text comparison is used constantly in software development. Code review involves examining diffs between the current version of a file and proposed changes, and version control systems like Git use diffs as their fundamental representation of changes. Developers compare configuration files between environments to identify unexpected differences. Technical writers compare documentation between versions to find what was added, removed, or reworded.
Beyond software, text diff is used by lawyers comparing contract drafts to identify every word that changed between negotiation rounds. Journalists and editors use text comparison to track revisions made by editors. Translators compare source texts to updated versions to identify which passages need to be retranslated. Any professional workflow that involves iterative text revision benefits from a reliable diff tool.
How to Use Text Diff Checker
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Paste your original text into the left panel.
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Paste the modified version into the right panel.
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The diff result appears below automatically.
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Green lines are additions, red lines are removals, and unchanged lines appear in grey.
Frequently Asked Questions
How does the text diff tool work?
It uses a line-by-line comparison algorithm (Longest Common Subsequence) to find what lines were added, removed, or unchanged between your two texts.
Can I compare code with the diff checker?
Yes. The diff tool works with any plain text including source code, JSON, configuration files, and documents. Lines are compared as-is including indentation.
Is there a size limit for text comparison?
There is no hard limit, but very large texts (thousands of lines) may be slower since comparison runs in your browser. For most use cases it is instant.