Diff Checker

About Diff Checker

Compares two blocks of text and highlights the differences line by line. Additions appear in green, deletions in red, and unchanged lines are shown in neutral styling. The output format is similar to git diff — familiar to most developers without any explanation needed. The comparison is line-based by default, which works well for code, configuration files, JSON, YAML, and structured text. Each changed line shows the full content of both the original and modified version side by side, making it easy to see exactly what changed even when the differences are small character-level edits within a long line. Practical use cases: comparing two versions of a config file to understand what changed between environments, reviewing API responses across two different requests to spot unexpected field changes, verifying that a refactored function produces the same output as the original, or spot-checking that a template was applied consistently across multiple files. For JSON specifically, the best workflow is to format both inputs through the JSON Formatter first — this normalizes whitespace and key ordering so the diff reflects only content changes, not formatting differences.

How to Use Diff Checker Online

1. Paste your data into the input field above
2. The result appears instantly in the output area
3. Click "Copy" to copy the result to your clipboard

Compare two texts and highlight differences. Runs 100% client-side — no data is sent to any server.

Frequently Asked Questions