Text Diff Checker
Compare two texts instantly and see every difference highlighted. Paste your original and modified text below.
How to Use the Text Diff Checker
Our diff checker makes it easy to spot changes between two versions of a document. Follow these simple steps:
- Enter your texts – Paste the original version into the left box and the modified version into the right box.
- Click "Compare Now" – The tool instantly highlights all differences line by line.
- Review the differences – Green lines show text that was added (present only in the modified version). Red lines show text that was removed (present only in the original). Unchanged lines appear in normal text.
- Swap or clear – Use the "Swap Texts" button to exchange the two texts, or "Clear" to reset everything.
- Copy or download – Save the diff report as plain text for your records.
Understanding the Diff Output
The diff algorithm works line by line. Here's what the colors mean:
| Color / Indicator | Meaning |
|---|---|
| Green background | Line was added in the modified version (not present in original). |
| Red background | Line was removed from the original version (not present in modified). |
| Normal / dimmed text | Line is unchanged between both versions. |
Common Use Cases
| Use Case | Description |
|---|---|
| Code version control | Compare old and new code snippets to see exactly what changed before committing. |
| Document editing | Review edits made to contracts, essays, or reports. |
| Plagiarism & similarity check | Quickly spot copied or modified passages between two texts. |
| Configuration comparison | Find discrepancies between two configuration files or logs. |
| Content updates | See what was added or removed when updating website copy or articles. |
💡 Pro Tip: The diff checker is fully client‑side. Your texts never leave your browser – perfect for sensitive documents or proprietary code.
Frequently Asked Questions
Is the Text Diff Checker really free?
Yes, completely free! No login, no watermarks, no limits. Use it as much as you need.
How accurate is the diff algorithm?
Our tool uses a line‑based Longest Common Subsequence (LCS) algorithm, which is the standard for diff utilities. It accurately shows inserted and deleted lines, even with complex changes.
Can I compare large files?
Yes, but performance depends on your device. For very large texts (tens of thousands of lines), the browser might slow down. For most documents (up to a few thousand lines), it works instantly.
Does this support character‑level differences?
Currently, the diff is line‑based, which is best for most document comparisons. For character‑level diff, you would need a specialized tool, but our line diff still highlights changes clearly.
Is my data private?
Absolutely. All processing happens inside your browser. We never store, log, or transmit your texts. Your data stays completely private.