What is a JSON diff checker?

A JSON diff checker compares two JSON documents and highlights the differences — which keys were added, removed, or had their values changed. It's useful for debugging API responses, reviewing configuration changes, comparing database records, or tracking how a JSON structure evolved over time.

How does the JSON diff tool work?

The tool flattens both JSON objects into key-path/value pairs (e.g., 'address.city' → 'Seoul') and then compares them. Added keys appear in green, removed keys in red, and changed values in yellow. Keys present in both with the same value are shown as equal (gray).

Can I compare nested JSON objects?

Yes. The tool recursively flattens nested objects and arrays into dot-notation paths (e.g., 'user.address.city', 'tags[0]'). Each leaf value is compared individually, so you can see exactly which nested property changed even in deeply structured JSON.

Is my JSON data kept private?

Absolutely. All comparison happens entirely in your browser using JavaScript. No JSON data is sent to any server, making it safe to use with API keys, credentials, or any sensitive configuration data.

Can I edit the JSON directly in the tool?

Yes. You can type or paste JSON into either text area, and the tool will validate it in real time. If the JSON is invalid, an error indicator appears below that field. The comparison only runs when you click the Compare button.

JSON差分チェッカー

2つのJSONオブジェクトを並べて比較し、追加・削除・変更された項目を即座に確認します。

JSON A（元のデータ）

JSON B（変更後）

使い方

2つのJSONオブジェクトを並べて比較し、追加・削除・変更された項目を即座に確認します。

1Paste your original JSON into the left text area labeled 'JSON A'.
2Paste the modified JSON into the right text area labeled 'JSON B'.
3Click Compare to generate the diff. Added keys appear in green, removed in red, and changed values in yellow.
4Toggle 'Show unchanged' to hide or show keys that are identical in both JSON objects.
5Click 'Copy diff' to copy a plain-text summary of all changes to your clipboard.

主な機能

Flat key-path comparison — nested objects and arrays are flattened to dot-notation paths for easy scanning
Color-coded results — green for added, red for removed, yellow for changed, gray for equal
Inline JSON editing — type or paste directly into either panel with real-time validation
Copy diff summary — export all changes as plain text with +/−/~ prefixes

よくある質問

詳しく読む

JSON Diff Checker Guide — Compare JSON Objects Online