Diff Checker
Compare two blocks of text or code side-by-side to find every difference with word-level highlighting and synchronized scrolling.
Online Diff Checker — Compare Text & Code
Comparing two versions of a document, configuration file, or code snippet is one of the most fundamental tasks in software development. Our Diff Checker provides professional-grade comparison with word-level and character-level inline highlighting, synchronized side-by-side scrolling, and both split and unified view modes.
Unlike many diff tools that require software installation or server-side processing, StringToolsApp's Diff Checker runs entirely client-side in your browser using the proven Myers diff algorithm. Your code and text never leave your machine — making it safe for comparing proprietary source code, configuration secrets, and sensitive documents.
Diff Checker Features
- Word-Level Highlighting — See exactly which words changed within modified lines, not just that a line was changed.
- Character-Level Highlighting — Spot single-character differences like typos, extra spaces, or changed punctuation.
- Split View — Side-by-side comparison with synchronized scrolling so both panels stay aligned.
- Unified View — Single-column diff view with additions and removals inline, similar to git diff output.
- Hide Unchanged Lines — Focus only on the differences by collapsing unchanged content.
- Statistics — See the total number of additions, removals, and unchanged lines at a glance.
Common Use Cases
Code Review — Compare the original and modified versions of a function or file to understand what changed before merging a pull request.
Configuration Auditing — Compare server configurations, .env files, or nginx configs between staging and production environments to catch discrepancies.
Document Versioning — Compare two drafts of a legal document, contract, or proposal to track every edit made by collaborators.
Database Migration Scripts — Verify that migration scripts match expected schema changes by comparing before and after SQL statements.
API Response Debugging — Compare expected and actual API responses to identify missing fields, changed values, or structural differences.
Frequently Asked Questions
How does the diff checker work?
The diff checker uses the Myers diff algorithm to compare two text inputs and highlight additions, removals, and changes at the word, character, or line level.
Can I compare code files?
Yes. The diff checker works with any text including source code in any programming language, configuration files, markdown, and plain text.
Is my code safe when using the diff checker?
Yes. All comparison is done entirely in your browser. No data is ever uploaded to any server, making it safe for proprietary source code and confidential documents.