JSON Formatter

About the JSON Formatter

JSON (JavaScript Object Notation) is the lingua franca of modern web APIs, configuration files, and data interchange. It is compact, human-readable, and supported by virtually every programming language — but the moment JSON is minified, logged as a single line, or copied out of a terminal, it becomes almost impossible to read by eye. This formatter takes any JSON input and expands it into a properly indented, syntax-highlighted structure so you can scan the shape of the data at a glance.

It also validates as it formats. A missing comma, a stray trailing bracket, or an unquoted key will produce a clear error message pointing at the location in the input, which is faster than pasting into a code editor and waiting for a linter to catch up. Everything runs entirely in your browser, so nothing you paste is sent to a server — an important detail when the payload contains API keys, session tokens, or personal data pulled from a production log.

The formatter is useful for both quick inspections and deeper work: diffing two API responses, checking whether a webhook payload is well-formed, or cleaning up a configuration file before committing it to a repository.

How to Format and Validate JSON

1. Paste your JSON into the input area above — it can be minified, pretty-printed, or anything in between.
2. The formatted output appears immediately, with consistent indentation and line breaks around every key and array element.
3. If the input is invalid, an error message appears with the character position of the first problem so you can jump straight to the broken part.
4. Copy the formatted output with the copy button, or clear both panels to start fresh with another payload.

Examples

{"user":{"id":42,"name":"Ada","roles":["admin","editor"]},"ok":true}

{
  "user": {
    "id": 42,
    "name": "Ada",
    "roles": ["admin", "editor"]
  },
  "ok": true
}

{"name": "Ada", "age": 36,}

Common Use Cases

• Inspecting webhook or third-party API responses pasted from a terminal or browser DevTools.
• Cleaning up machine-generated JSON before checking it into a repository or sharing it in a pull request.
• Quickly confirming whether a suspicious string from a log file is valid JSON at all.
• Teaching or documentation — making small JSON snippets legible for screenshots and code blocks.
• Reviewing package.json, tsconfig.json, or other config files that have grown large over time.

Tips

• Strict JSON has no trailing commas, no single quotes, and no comments. If your input has any of those, it is actually JSON5 or JavaScript — strip them before validating.
• Very large payloads (tens of megabytes) can lag in the browser. For those, consider a command-line tool such as jq, which streams and handles arbitrary size.
• If you are redacting values before sharing, replace them with placeholder strings rather than deleting them — that keeps the structure valid and still scannable.

Frequently Asked Questions