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JSON Editor Online — Format, Validate & Transform JSON

A fast, free JSON editor that lets you format, validate, minify, and transform JSON directly in your browser. Switch between code view and tree view, fix syntax errors with one click, and explore deeply nested objects without losing your place. Everything runs locally — no data is uploaded to any server, so it is safe for API responses, configuration files, and tokens during debugging.

Features

  • Format & beautify

    Pretty-print JSON with consistent indentation and key ordering.

  • Validate & repair

    Catch syntax errors with inline messages and auto-repair common mistakes like trailing commas.

  • Tree view

    Navigate large JSON documents with a collapsible, searchable tree view.

  • 100% client-side

    Your JSON never leaves the browser. Safe for sensitive payloads and API debugging.

How to format JSON online

Paste, format, and validate any JSON document in three steps.

  1. Paste your JSONCopy any JSON string and paste it into the editor on this page.
  2. Format or minifyClick Format to pretty-print, or Minify to strip whitespace for production payloads.
  3. ValidateThe editor highlights syntax errors with line numbers. Fix them in place or use the auto-repair option.
  4. Copy the resultUse the copy button to grab the formatted JSON, or switch to tree view to inspect the structure.

Examples

Pretty-print a compact API response

Input
{"id":42,"name":"Alice","roles":["admin","editor"],"active":true}
Output
{
  "id": 42,
  "name": "Alice",
  "roles": ["admin", "editor"],
  "active": true
}

Minify JSON for transport

Input
{
  "items": [1, 2, 3],
  "total": 3
}
Output
{"items":[1,2,3],"total":3}

Minified output is roughly 30–50% smaller and faster to transfer over the network.

Frequently Asked Questions

Is this JSON editor free to use?
Yes. EasyDev is completely free and requires no account or sign-up.
Is my JSON data uploaded to a server?
No. The editor runs entirely in your browser using JavaScript. Your JSON never leaves your machine, which makes it safe for API responses, secrets, and customer data.
What is the maximum file size I can format?
There is no hard limit, but very large documents (tens of megabytes) may make the browser sluggish. For multi-megabyte payloads, the tree view performs better than code view.
Can I validate JSON against a schema?
The editor validates JSON syntax (structure, quoting, commas). Schema-level validation against a JSON Schema is on the roadmap.
Does it work offline?
Yes. Once the page is loaded, the editor works offline because no network calls are made during formatting or validation.
What is the difference between format and minify?
Format adds whitespace and indentation so the document is easy to read. Minify removes all unnecessary whitespace so the document is as small as possible — useful for API payloads and storage.