Diff Checker
Compare two texts and see every difference highlighted. Line-by-line diff with additions, deletions, and modifications color-coded. Free, private, runs in your browser.
Fast & Free
Process files up to 100MB at no cost. No account needed.
Secure
Files are encrypted and automatically deleted after processing.
High Quality
Optimized algorithms for the best quality-to-size ratio.
About Diff Checker
Why you need a diff checker
Comparing two versions of a document, config file, code snippet, or contract to find what changed is tedious and error-prone by eye — especially in long documents where changes are scattered across dozens of pages. A diff checker instantly highlights every addition, deletion, and modification so nothing gets missed, even in documents with thousands of lines.
How this tool works
Uses a longest common subsequence (LCS) diff algorithm — the same mathematical approach behind Git's diff — to compute the minimum set of changes between two texts. Results are shown with color-coded highlighting: green for added lines, red for removed lines. Toggle options let you ignore whitespace differences and case sensitivity depending on what kind of comparison you need.
Use cases beyond code
While developers use diff tools constantly for code review, they're equally useful for writers comparing draft revisions, lawyers reviewing contract changes to see exactly what a counterparty modified, students checking edits on papers, and anyone who needs to verify what changed between two versions of any text document.
Common uses for Diff Checker
- Comparing two versions of source code to review changes before committing
- Reviewing contract revisions to see exactly what a counterparty changed
- Checking configuration file differences between staging and production environments
- Verifying copy edits on articles, blog posts, or marketing materials
- Comparing API responses between two endpoints or two time periods
Frequently Asked Questions
Can I compare code files?
Yes. The diff checker works with any text including source code in any programming language. It doesn't provide language-specific syntax highlighting, but the diff highlighting (additions in green, deletions in red) works on any text content.
What's the difference between line-level and character-level diff?
Line-level diff shows which entire lines were added, removed, or left unchanged — good for a quick overview. Character-level diff goes deeper and highlights the specific words or characters within a line that changed. Use line-level for broad comparison and character-level when you need to find the exact change.
Can I compare files directly?
Currently you paste text into both fields. To compare files, open them in any text editor, copy the contents, and paste into the tool. File upload support may be added in a future update.
Is there a size limit?
No hard limit. The tool handles texts with 10,000+ lines. Very large comparisons may take a moment to process since everything runs locally in your browser.