Text Diff Checker
Use this text diff tool to compare two blocks of text side by side and highlight every difference between versions.
About Text Diff Checker
Spotting changes between two versions of a document, configuration file, or code snippet can be painstaking. Our Text Diff Checker compares two blocks of text side by side and highlights every difference so you can see exactly what was added, removed, or changed.
How it works
Paste the original text in the left panel and the modified text in the right panel, then click Compare. The tool performs a line-by-line diff and color-codes the results: red for removed lines, green for added lines, and no highlight for lines that match. The visual output makes it easy to scan even long documents for changes.
Use cases
Writers use the diff checker to review edits between drafts. Developers compare configuration files or API responses across environments. System administrators verify that deployment scripts match their approved versions. If you also need to make bulk edits, the find and replace tool pairs well with this one.
Privacy and performance
The entire comparison runs in your browser. No text is uploaded to a server, making it safe for confidential documents, proprietary code, and sensitive data. Because there is no network round-trip, results appear the moment you click Compare, even for documents with thousands of lines.
You can also run a quick word count on each version to see if the length changed alongside the content.
Frequently Asked Questions
How does the diff comparison work?
The tool performs a line-by-line comparison of the two texts. Lines that exist only in the original are highlighted in red, lines that exist only in the modified version are highlighted in green, and unchanged lines are shown without highlighting.
Can I compare code with this tool?
Yes. The diff checker works with any plain text, including source code, configuration files, JSON, CSV, and more. It compares line by line, which is the same approach used by tools like git diff.
Is there a size limit?
There is no hard limit, but very large texts (over 10,000 lines) may slow down your browser since the comparison runs entirely client-side. For most documents, results appear instantly.
Does the tool detect moved lines?
The current implementation compares lines by position. If a line was moved to a different location, it will appear as a deletion in the original position and an addition in the new position, similar to a basic unified diff.