Diff Checker
Free diff checker to compare two texts or code files side by side or unified, with word-level highlights, ignore-whitespace options and stats. Private, local.
- No upload — 100% private
- Instant, on your device
- Free, no sign-up
- Works offline once loaded
How it works
How to use Diff Checker
Paste the original text on the left and the changed text on the right, or open files.
Choose Side by side or Unified view.
Optionally ignore whitespace or case and collapse unchanged lines.
Review the +added / −removed counts and copy or download the result as a .diff patch.
Why use it
Why use our Diff Checker tool
Side by side or unified
Classic two-column comparison or a git-style unified view with old and new line numbers.
Word-level highlights
Changed lines show exactly which words were edited, not just that the line differs.
Ignore whitespace & case
Skip indentation and spacing changes or letter case to focus on real edits.
Collapse unchanged lines
Long identical stretches fold away, with one click to expand them.
Patch export
Copy or download a standard unified .diff that works with git apply and patch.
FAQ
Frequently asked questions
How do I compare two files?
Use Open on each side to load a file from your device, or paste the contents. The comparison updates automatically.
What does ignore whitespace do?
Lines are compared after collapsing runs of spaces and tabs and trimming the ends, so re-indented code or trailing spaces don't show up as changes.
What is a unified diff?
A unified diff lists removed lines prefixed with − and added lines with +, surrounded by unchanged context. It's the format used by git diff and code review tools.
Are my texts uploaded to compare them?
No. The comparison runs entirely in your browser, which makes it safe for contracts, config files and private source code.
Can it compare very large files?
Yes, within reason. Files with tens of thousands of lines work well; if two huge files are extremely different, the comparison stops after a few seconds and asks you to narrow it down.
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