JSON Formatter

Make structured data readable or compact. Syntax errors appear beside the editor instead of being silently ignored.

Free to useCalculated in your browserv0.2.1 · Method documented September 12, 2026

Your inputs

Changes update automatically
Saved only when you choose; never uploaded
Save these inputs as a project

Optional, unencrypted storage in this browser only. Do not save secrets on a shared device. Nothing is saved automatically.

My workspace →

Know the limits. JavaScript number precision applies. Integers outside ±9,007,199,254,740,991 can change; duplicate object keys retain the last value. This is not a lossless canonicalizer.

How it works

The standard JavaScript parser validates syntax. The formatter then serializes with two spaces, four spaces or no extra whitespace. Comments and trailing commas are not valid JSON.

JSON.parse(input) → JSON.stringify(value, indentation)

Try the example

The starter inputs above produce:

{
  "project": "ToolNuvilo",
  "tools": 20,
  "free": true
}

Change the inputs to match your own situation. The result is an estimate or text transformation, not a substitute for reviewing your source data.

A few useful details

Can I paste API keys?

The release makes no input-upload requests, but avoid putting secrets into any page unless you trust its deployment and your browser environment.

Does it support JSON5 or comments?

No. This tool uses strict standard JSON parsing.

Do I need an account?

No. This release runs without an account, API key or payment. Saving a favorite stores only the tool’s identifier in this browser, not your inputs.