What indentation does the formatter use?

The formatter uses 2-space indentation, which is the most common standard for JSON.

Can I validate JSON without formatting?

Yes. Validation happens automatically as you type. Errors are shown even before you click a format button.

Is there a size limit?

No hard limit — processing is in your browser, so very large JSON files (10 MB+) may be slow on older devices.

Invalid JSON — what should I fix?

Check for: trailing commas before ] or }, unquoted keys, single quotes (use double quotes), or missing commas between elements. The error message usually points to the line.

Is there a tree view?

Yes. After formatting valid JSON, you can switch to the "Tree" view to browse the structure with expand/collapse for objects and arrays.

JSON整形・検証

Format and validate JSON with proper indentation or minify it for production. The validator highlights syntax errors so you can fix them fast. Developers often handle sensitive payloads — for this formatter, processing runs in your browser and we don't send your JSON to our servers for this step.

無料 · 制限なし · ブラウザで処理

使い方

1Paste your JSON into the input textarea.
2Choose "Pretty Print" for readable formatting or "Minify" for compact output.
3View any validation errors highlighted below the input.
4Copy the formatted output with one click.

よくある質問

What indentation does the formatter use?: The formatter uses 2-space indentation, which is the most common standard for JSON.
Can I validate JSON without formatting?: Yes. Validation happens automatically as you type. Errors are shown even before you click a format button.
Is there a size limit?: No hard limit — processing is in your browser, so very large JSON files (10 MB+) may be slow on older devices.
Invalid JSON — what should I fix?: Check for: trailing commas before ] or }, unquoted keys, single quotes (use double quotes), or missing commas between elements. The error message usually points to the line.
Is there a tree view?: Yes. After formatting valid JSON, you can switch to the "Tree" view to browse the structure with expand/collapse for objects and arrays.