Text Diff Checker

Compare two texts and highlight every difference — line by line or word by word

📄 Original Text

📄 Modified Text

Enter text in both fields and click Compare

Frequently Asked Questions

What is a text diff checker?
A text diff checker compares two blocks of text and highlights the differences between them. It shows which lines or words were added, removed, or changed.
How does line-by-line comparison work?
Line-by-line comparison splits both texts into lines and identifies which lines are unique to each text or modified. Removed lines are shown in red, added lines in green.
What is word-by-word diff mode?
Word-by-word mode goes deeper than line comparison. For each changed line, it identifies the specific words that differ, highlighting only the changed portions.
What is a unified diff view?
Unified view shows both texts merged into a single column with + and - prefixes indicating additions and removals, similar to Git diff output.
Is my text stored or sent to a server?
No. All comparison happens entirely in your browser. Your text never leaves your device.
Can I compare code files?
Yes. You can paste any text including source code. The diff checker handles all plain text formats.
What's the difference between split and unified view?
Split view shows both texts side by side with differences aligned. Unified view merges them into one column with change indicators.
Does it support large text files?
The tool handles texts up to several hundred KB efficiently. For very large files (MB+), performance may vary depending on your browser.

📋 How to Use the Diff Checker

1. Paste your original text: Enter the original or "before" version of your text in the left text area. This could be the previous version of a document, code, configuration file, or any text content you want to compare.

2. Paste the modified text: Enter the new or "after" version in the right text area. The diff checker will compare both texts and highlight every addition, deletion, and change between them.

3. Choose your view: Toggle between "Unified" view (all changes in a single column with +/- indicators) and "Split" view (side-by-side comparison). Unified is great for reading through changes sequentially; split view makes it easy to compare corresponding lines visually.

4. Enable word-level diff: Turn on "Word Diff" to see exactly which words changed within a modified line. Instead of marking the entire line as changed, it highlights only the specific words that were added or removed — perfect for reviewing edited prose or refactored code.

5. Review the statistics: The summary bar shows the count of added lines, removed lines, and unchanged lines at a glance. If no differences are found, a confirmation message is displayed. All processing runs locally in your browser.

❓ Frequently Asked Questions

What is a diff checker?
A diff checker compares two text inputs and highlights the differences between them. It shows which lines were added, removed, or modified. Diff checkers are essential for code review, document editing, and version control workflows.
What is the difference between unified and split diff view?
Unified view displays all changes in a single column with + and - prefixes. Split view shows both texts side by side with changes aligned, making it easier to compare corresponding sections visually.
What is word-level diff?
Word-level diff identifies exactly which words within a changed line were added or removed. Instead of highlighting the entire line, it marks only the specific words that differ, making it much easier to review small edits.
Is my text data sent to a server?
No. All text comparison and diff computation happens entirely in your browser using JavaScript. Your text content is never transmitted over the network or stored anywhere.
How large files can the diff checker handle?
The tool handles most text files comfortably up to a few hundred kilobytes. For very large files (megabytes), a command-line tool like git diff or diff may be more efficient.
Can I compare code files?
Yes. The diff checker works with any plain text, including source code in any programming language. Paste your code from two versions and the tool will highlight the differences.
What algorithm does the diff checker use?
This tool uses a Longest Common Subsequence (LCS) algorithm to find the optimal set of differences between two texts. LCS efficiently identifies which lines are shared and which are unique, producing a minimal and readable diff output.
Can I use this to compare JSON or configuration files?
Absolutely. Any plain text works — JSON, YAML, XML, CSV, INI, .env files, and more. For structured formats like JSON, format both versions first for consistent line-by-line comparison.

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