Diff Checker – Compare Text & Code
Compare two blocks of text, code, or configuration side-by-side and instantly spot every addition, deletion, and modification. Supports character-level, word-level, and line-level diff modes. Ideal for code reviews, proofreading document revisions, comparing configuration files, and catching merge conflicts. All comparison is done in-browser — no files uploaded.
How Diff Works
A diff algorithm compares two sequences of text and computes the shortest list of changes (insertions and deletions) needed to transform one into the other. The most widely used algorithm is the Longest Common Subsequence (LCS) algorithm, which powers Git, diff command-line tools, and code review platforms like GitHub and GitLab.
Changes are colour-coded: green for additions, red for deletions, and unchanged lines remain neutral.
Diff Modes Explained
Character Mode
Highlights every individual character change. Best for detecting typos, punctuation errors, or subtle edits in code.
Word Mode
Highlights whole-word changes. Ideal for comparing document drafts and identifying added or removed words.
Line Mode
Shows which entire lines changed. Perfect for config files, code blocks, and structured data.
Tips & Tricks
- Enable Ignore Whitespace to focus on content changes, not formatting
- Enable Ignore Case when comparing text where capitalisation does not matter
- Use Line Mode to compare JSON, YAML, or config files line by line
- Use Word Mode to review changes in essays, articles, or contracts
- Paste minified code, then format it before comparing for cleaner results
Common Diff Checker Use Cases
Code Review
Compare two versions of a function or file to spot what changed between commits.
Document Edits
Review changes between draft versions of contracts, articles, or documentation.
Config Files
Spot differences in YAML, JSON, TOML, or INI configuration between environments.
Plagiarism Check
Detect copied or paraphrased text by comparing it against an original source.
Frequently Asked Questions
Related Tools
Text Comparison and Diff Checking for Developers
Diff checking — comparing two versions of text to identify differences — is one of the most fundamental operations in software development. Every code review, every merge request, and every deployment pipeline depends on accurate diff detection. Version control systems like Git use sophisticated diff algorithms (Myers, patience, histogram) to compute the minimal set of changes between file versions. Our diff checker brings this capability to the browser, letting you paste any two text blocks and instantly see additions, deletions, and modifications highlighted in a clean, side-by-side or unified view.
Beyond Code: Diff Checking for Configuration and Documentation
Diff checking is not just for source code. Configuration files (JSON, YAML, XML, environment variables) frequently change between environments, and spotting unintended differences prevents deployment failures. Legal documents, contracts, and policy pages require precise change tracking. API response comparison helps debug regressions — paste the expected and actual responses to instantly identify discrepancies. Database schema migrations, Terraform plans, and Kubernetes manifests all benefit from visual diffing before applying changes to production.
Integrating Diff Checking into Your Workflow
A browser-based diff tool complements your IDE and CLI diff tools by providing a shareable, zero-setup comparison environment. Paste a colleague's config alongside yours to debug environment-specific issues. Compare formatted and minified JSON using the JSON Viewer first, then diff the formatted versions. Check YAML configurations with the YAML Viewer. Transform text case before comparison using the Text Transformer. Explore all tools on the homepage.