Online JSON Diff Tool

Compare Two JSON Objects Side-by-Side

Our JSON Diff tool lets you instantly compare two JSON documents and see exactly what changed. Paste your original JSON on the left and the modified version on the right, then click Compare JSON to get a color-coded diff view powered by Monaco Editor — the same editor that runs in VS Code.

• Green highlights: Lines added in the modified version.
• Red highlights: Lines removed from the original.
• Inline word diffs: Character-level changes within modified lines.
• Auto-format: Both inputs are normalized to 2-space indented JSON before comparison, eliminating false positives from whitespace-only differences.

How to Use the JSON Diff Checker

1. Paste your original JSON into the left textarea.
2. Paste the modified JSON into the right textarea.
3. Click Compare JSON. Both documents are validated and formatted before diffing.
4. Review the Monaco diff view below — green for additions, red for deletions.
5. Use Swap to reverse the comparison direction, or Copy Left/Right to grab the normalized output.

Common JSON Diff Use Cases

• API response changes: Compare responses between production and staging environments.
• Config file auditing: Spot differences between package.json, tsconfig.json, or environment configs.
• Data migration validation: Verify that a transformed or migrated JSON dataset matches the expected structure.
• LLM output review: Compare structured outputs from LLMs across different prompt versions.
• Schema evolution: Track how a JSON schema changes between API versions.

Why Use a JSON-Specific Diff Tool?

Generic text diff tools like git diff or Unix diff treat JSON as plain text. This means two JSON objects that are semantically identical can produce confusing diffs simply due to key ordering or indentation style. Our JSON diff checker normalizes both inputs first — parsing and re-serializing with consistent 2-space indentation — so you only see meaningful differences.

All comparison is done 100% client-side in your browser. Your JSON data is never sent to any server.