JSON/XML/CSV Tools

JSON Toolkit

Pretty-print, validate, minify, or diff JSON online without uploading. Free toolkit for API payloads, fixtures, and webhook debugging.

This JSON toolkit puts format, validate, minify, and diff on one page. Paste a payload, choose Mode, and keep staging data in your browser while you clean or compare documents.

About JSON Toolkit

Minified JSON travels well and reads poorly. Format mode restores indentation so nested objects and arrays are scannable—the same job you would do in an editor, without switching apps.

Validate mode surfaces parse errors instead of a blank failure. Minify strips whitespace when you need compact fixtures. Diff compares two documents so field drift between environments is obvious.

Engineers reach for this when Postman, DevTools, or CI logs only show compact JSON. Typical paste-and-run transforms stay local, which matters for tokens and staging fields.

How to Use JSON Toolkit

  1. Paste JSON into the input field.
  2. Select Format, Validate, Minify, or Diff under Mode.
  3. For Diff, paste the second document in the secondary field.
  4. Run the tool, then copy or download the output.

If Format fails, remove trailing commas, single quotes, or comments—standard JSON rejects them.

Common Use Cases

Debug API bodies

Pretty-print responses before reading nested error objects.

Review fixtures

Format seed JSON so pull-request diffs stay meaningful.

Spot drift

Diff staging vs local payloads when a field changed shape.

Compact storage

Minify fixtures that do not need human whitespace.

Tips and best practices

Random Data Hub keeps JSON work free and local, beside converters and mock-data tools on the same site.

Frequently Asked Questions

Quick answers about how this tool works and when to use it.

Does this upload my JSON?

No. Format, validate, minify, and diff run in your browser for normal paste workflows.

What about duplicate keys?

JSON.parse keeps the last value for a repeated key—that is standard language behavior.

When do I use Diff?

Use Diff to compare two documents; use Format when you only need readable indentation.

Can I minify after formatting?

Yes. Switch Mode to Minify and run again.

What does Json Formatter create?

Json Formatter creates json formatter results you can copy into forms, fixtures, demos, or design files. Adjust the on-page options, generate a batch, and regenerate until the output fits your scenario.