Compare text & documents with instant precision
Spot line, word, and character differences across two text versions or uploaded Word (.docx, .doc) and text (.txt) files. Evaluated 100% in your browser without transmitting a single byte to an external server.
.patch diff file or copy results directly.
Built for precision document & text comparison
Unlike online services that send your confidential documents to unknown cloud backends, TopToolLab Diff Checker executes the Myers differential algorithm locally inside your web browser.
.docx, .doc, and .txt documents on either side. Modern Word documents are parsed via client-side XML DOM traversal, extracting paragraphs and tables cleanly into plain text.
.patch) ready for version control or developer handoff.
Frequently asked questions
Straight answers about how the diff algorithm processes files, handles formatting, and safeguards your confidentiality.
Is my text or uploaded Word document sent to any server?
No. Everything runs 100% inside your local browser tab. The text parsing, Word document reading, and difference computation use standard browser APIs (FileReader, WebAssembly, and local JavaScript).
You can verify this yourself by opening Chrome or Edge DevTools, switching to the Network tab, and clicking "Compare Difference" — no outbound HTTP requests will be created. The tool even continues working completely offline once the page has loaded.
How does the file upload feature extract text from .docx and .doc files?
For modern Microsoft Word .docx files, the browser opens the OpenXML package and parses the internal word/document.xml text stream via Mammoth.js, extracting paragraphs, line breaks, and table contents without requiring Microsoft Office.
For legacy binary .doc files (Word 97-2003), an in-browser binary stream scanner reads the document bytes to extract Unicode and ASCII text blocks directly into the input editor.
What is the difference between Split (Side-by-Side) and Unified views?
Split view aligns the original version on the left and the modified version on the right with twin line numbers. Unchanged lines stay parallel, making structural shifts, deletions, and additions immediately intuitive to the human eye.
Unified view collapses both files into a single continuous stream, placing deleted lines (highlighted in red with a - sign) directly above added lines (highlighted in green with a + sign). This format matches Git pull request diffs and standard patch files.
Can I ignore minor changes like trailing spaces or letter casing?
Yes. Use the Ignore Case checkbox to treat uppercase and lowercase characters as identical (e.g., "Apple" equals "apple").
Similarly, enable Ignore Whitespace to eliminate noisy diffs caused by differing tab indentation, Windows (CRLF) vs. Unix (LF) line breaks, or trailing spaces at the end of paragraphs.
What file formats and sizes are supported?
You can upload .txt, .docx, and legacy .doc files, or paste any text or code snippet (JSON, Markdown, Python, HTML, XML, CSV, etc.) directly into the text areas.
Because processing happens in memory, documents with tens of thousands of words are processed in fractions of a second. For massive files (over 50,000 lines), computation takes 1–3 seconds depending on your device's CPU.
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