Text Diff Checker

Compare two text documents to instantly spot additions, deletions, and modifications.

Whenever possible, your data never leaves your device. Your security is our priority.

Comparison Engine

Original Text

Modified Text

About this Tool

The Text Diff Checker is a visual comparison tool that highlights the exact differences between two pieces of text. It is invaluable for programmers reviewing code changes, writers tracking manuscript edits, or anyone trying to find a subtle typo between two similar documents.

This tool uses a custom implementation of the Longest Common Subsequence (LCS) algorithm to compare your text entirely within your browser memory.

Performance Limit: Because LCS math scales exponentially, this tool has a safety cap of 4,000 tokens (words or lines) per input to prevent your browser from freezing. For massive logs, compare them in chunks!

How to Use

Input Original Text

Paste the older or original version of your text into the left text box.

Select Mode

Choose 'Word-by-Word' for standard paragraphs and essays, or 'Lines' to evaluate code snippets or sentence-by-sentence changes.

Compare & Review

Click 'Compare Texts'. Deletions will be highlighted in red with a strikethrough, and additions will be highlighted in green.

Frequently Asked Questions

If you are looking for specific typo fixes (like a single changed letter), use Word-by-Word. If you want to see which entire sentences or lines of code were rewritten, use Lines.

No. The entire mathematical comparison algorithm is downloaded to your device when you load the page. Your sensitive code or private documents never leave your browser.

Longest Common Subsequence is a classic computer science algorithm used to find the longest sequence of characters (or lines) that appear in the same order in both strings. By finding what stayed the same, we can calculate what was added or removed.