OptiDrop

Text Diff Checker — Compare Two Texts Online Free

Paste two texts side by side and instantly see what changed. Additions highlighted in green, deletions in red. No uploads, no sign-up — everything stays in your browser.

Free Online Text Diff Checker

OptiDrop's Text Diff Checker compares two blocks of text line by line and highlights every difference instantly. Additions are shown with a green background and deletions with a red background and strikethrough, making it easy to spot what changed between two versions of any document, code file, or piece of writing.

How to Use the Text Comparison Tool

Paste or type the original text into the left textarea and the modified version into the right textarea. Click the Compare button, and the tool runs a line-by-line diff algorithm entirely in your browser. The results show each line color-coded: green for new additions, red with strikethrough for removed lines, and plain text for unchanged lines. A summary at the top tells you exactly how many lines were added, removed, or left unchanged.

Who Uses Text Diff Tools?

Text diff tools are essential for many workflows. Developers use them to review code changes before committing. Writers and editors compare drafts to track revisions. Legal professionals compare contract versions to spot changes in terms. Students check plagiarism or compare essay drafts. Data analysts verify data cleaning by comparing raw and processed datasets.

100% Private — No Uploads

Your text never leaves your browser. All comparisons happen locally using JavaScript, which means your confidential documents, source code, and private text remain completely secure. There is no file upload, no server processing, and no data stored anywhere. Close the tab and your data is gone.

Frequently Asked Questions

Paste your original text into the left textarea and the modified text into the right textarea, then click the Compare button. The tool performs a line-by-line comparison and highlights additions in green and deletions in red so you can instantly see what changed.
Yes, OptiDrop's Text Diff Checker is completely free. There is no sign-up, no file upload, and no usage limits. Everything runs directly in your browser, keeping your text 100% private on your device.
Absolutely. The entire comparison happens locally in your browser. Your text is never uploaded to any server or stored anywhere. Once you close the page, the data is gone. This makes it safe for comparing sensitive documents, code, contracts, and confidential text.
A text diff (short for difference) is a comparison of two blocks of text that identifies lines that have been added, removed, or changed. It is widely used by developers to review code changes, by writers to compare drafts, by legal professionals to review contract revisions, and by anyone who needs to quickly spot differences between two versions of a document.

Last updated: June 2026