About

Text Diff Checker

Compare two texts and highlight differences

Original1 lines
Modified1 lines

Enter original and modified text, then click Compare

About This Tool

Comparing text differences is a fundamental task in software development, content editing, and document review. Whether you are comparing two versions of a code file, reviewing changes in a configuration file, checking differences between API responses, or verifying text transformations, a reliable diff tool saves time and reduces errors. Our free online text diff checker compares two texts side by side and highlights every addition, deletion, and modification with color-coded indicators. The tool uses a diffing algorithm that produces clean, minimal diffs, making it easy to see exactly what changed between two versions. It supports plain text, code, JSON, XML, and any other text-based format.

How to Use

  1. Paste the original text into the "Original" (or "Before") panel on the left. This represents the baseline version you want to compare against.
  2. Paste the modified text into the "Modified" (or "After") panel on the right. This is the version with changes you want to identify.
  3. Click the "Compare" button to run the diff analysis. The tool will highlight additions in green, deletions in red, and unchanged text in the default color, showing you exactly what differs between the two versions.
  4. Use the navigation controls to jump between differences if the texts are long. The diff summary shows the total number of additions, deletions, and the overall change statistics.
  5. Copy the diff results or share the comparison using the generated link. You can also swap the two texts to view the diff from the opposite direction.

Frequently Asked Questions

Our diff checker uses the Myers diff algorithm (or a similar longest common subsequence approach), which finds the smallest set of changes needed to transform one text into another. It works by identifying the longest common subsequences between the two texts and marking everything else as additions or deletions. This produces clean, intuitive diffs that are easy to read and understand.
Yes. While the tool compares plain text, it works perfectly with source code in any language. Simply paste the two versions of your code into the left and right panels. The diff results will show line-level changes with syntax-appropriate formatting. For very large files, you may want to paste only the relevant sections to keep the comparison focused and readable.
The tool handles texts of several thousand lines efficiently. For extremely large files (over 10,000 lines), performance may vary depending on your browser and device. For best results with very large comparisons, consider comparing specific sections rather than entire files. All processing happens in your browser, so there are no server-side file size limits.
A line diff compares text line by line and marks entire lines as added, deleted, or unchanged. A word diff goes deeper and highlights individual word-level changes within a line, showing exactly which words were added or removed. Word-level diffing is more precise and useful for prose and documentation, while line-level diffing is standard for code comparisons.
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