Paste two texts above and click "Compare" to see the differences.
How to Compare Text Differences
- 1Paste or type your original text in the left "Original" textarea.
- 2Paste or type the modified text in the right "Modified" textarea.
- 3Click the "Compare" button to generate the diff result.
- 4Review the highlighted output — green lines are additions, red lines are removals, and plain lines are unchanged.
- 5Use the "Copy Diff" button to copy the unified diff output, or "Swap" to switch the two inputs.
Features
●Line-by-line diff comparison using LCS (Longest Common Subsequence) algorithm
●Color-coded output — additions in green, deletions in red
●Unified diff view with line numbers for both original and modified text
●Summary showing total lines added, removed, and unchanged
●Swap button to quickly reverse original and modified inputs
●Copy diff result to clipboard with one click
●Handles large texts with accurate diffing
●100% client-side — your data never leaves your browser
Frequently Asked Questions
What algorithm does this diff checker use?▼
This tool uses the Longest Common Subsequence (LCS) algorithm to compute line-by-line differences. LCS finds the longest sequence of lines common to both texts, then marks remaining lines as additions or deletions. This is the same foundational approach used by tools like git diff and GNU diff.
Can I compare code files with this tool?▼
Yes. The diff checker works with any plain text, including source code in any programming language. The monospace font and line numbers make it easy to read code diffs. Simply paste your original and modified code into the two text areas and click Compare.
Is there a size limit for the text I can compare?▼
There is no hard limit, but very large texts (tens of thousands of lines) may take longer to process since the LCS algorithm runs entirely in your browser. For most practical use cases — config files, code snippets, documents — performance is instant.
Is my data sent to a server?▼
No. All processing happens entirely in your browser using JavaScript. No text is uploaded, stored, or transmitted to any server. You can verify this by checking the network tab in your browser's developer tools.
What is a unified diff view?▼
A unified diff view shows all changes in a single column, with removed lines prefixed by '−' and added lines prefixed by '+'. Unchanged lines provide context. This format is widely used in version control systems like Git and is easy to read at a glance.
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