Text Diff Checker
📦 Text Diff Checker Source Code $3.99
Get the complete, ready‑to‑deploy HTML file with all styling and logic. This is the exact code powering the demo above — no dependencies, works offline, and 100% client‑side. Uses the Longest Common Subsequence (LCS) algorithm for accurate line‑by‑line comparison. Perfect for code reviews, document comparison, and version tracking. One‑time purchase, lifetime access.
What Is a Text Diff Checker?
Developers, writers, and editors frequently need to compare two versions of text — whether it's source code changes, document revisions, or configuration file updates. Manually scanning for differences is error‑prone and time‑consuming. This tool automates the comparison using the Longest Common Subsequence (LCS) algorithm, highlighting added lines in green, removed lines in red, and unchanged lines in gray. With options for case‑insensitive and whitespace‑ignoring comparisons, it adapts to your specific use case.
How to Use
- Paste your texts — the original version in the left textarea and the modified version in the right textarea.
- Toggle options — ignore case, ignore whitespace, or show/hide line numbers as needed.
- Click "Compare" — the diff result appears instantly with color‑coded lines.
- Swap texts with the Swap button, copy the diff result, or clear everything with the Clear button.
Frequently Asked Questions
How does the diff algorithm work?
The tool uses the Longest Common Subsequence (LCS) algorithm to find the longest sequence of lines that appear in the same order in both texts. Lines that are part of the LCS are marked as unchanged; lines not in the LCS are marked as added or removed.
Does this tool work offline?
Yes. The tool is fully self‑contained and runs entirely in your browser. Once the page loads, you can use it offline without any network connection.
Is my data sent to a server?
No. All processing happens entirely in your browser using JavaScript. Your text never leaves your device.
Disclaimer: This tool performs all operations locally in your browser. No data is stored, transmitted, or logged. You are responsible for ensuring you have the rights to process any data you upload.