Diff Checker
Compare two text blocks side-by-side. Highlights added, removed, and changed lines instantly.
How to Use
- Paste your original text in the left panel and the modified text in the right panel. You can also drag-and-drop text files or type directly into both sides.
- The tool instantly highlights differences line-by-line: green for added lines, red for removed lines, and inline character highlighting within changed lines. Use the navigation arrows to jump between differences quickly.
- Review the side-by-side or unified diff view, then copy either side's output or the full diff report. All comparison happens locally in your browser — no data leaves your device.
Frequently Asked Questions
- Is this a character-level or line-level diff?
- The tool does both — it first compares line-by-line, then within each changed line it highlights the exact character differences. This gives you the precision of character-level diffing with the clarity of line-level structure.
- Can I compare two files with different line endings (CRLF vs LF)?
- Yes, the tool normalizes line endings before comparison so you won't see false positives from line-ending differences. It handles Windows (CRLF), Unix (LF), and old Mac (CR) formats seamlessly.
- What if my texts are very large — will it slow down?
- The diff algorithm runs entirely in your browser. For texts up to a few thousand lines, performance is instant. For very large comparisons of 10K+ lines, you may notice a brief processing delay but it completes without uploading anything.