Skip to main content
Utilnivo

Developer

Utilnivo

Format JSON Online

Format, validate, and indent JSON online—free developer utility.

No registration
  • On your device

Browse more in Developer or all tools.

Why is my JSON invalid?

Common causes: trailing commas after the last property, single-quoted strings instead of double quotes, unescaped line breaks inside strings, and comments (JSON does not allow // or /* */). The formatter highlights the parse error line when the browser reports a position—fix that token first, then re-validate.

Private on your device

Your information stays on your device and is not uploaded.

Related tools

Format JSON online when you need readable structure fast. Paste minified payloads, fix syntax errors highlighted by the validator, and copy indented output for tickets, tests, or README examples.

Online formatters save time when you cannot open an IDE—support engineers and PMs use them for quick payload inspection.

Pair formatting with JSON compare when reviewing two API versions side by side.

How to use this tool

Paste JSON, run format, and review error messages if parsing fails. Copy or download the formatted text when valid.

Worked example

Example: format a 400 KB single-line log extract into indented JSON to find which array element failed schema validation.

When to use this

  • Support triage on customer JSON payloads.
  • Cleaning samples before publishing docs.
  • Teaching JSON structure in workshops.

Common examples

  • Minified API response from `curl` → indented JSON for diffing against staging.
  • Invalid trailing comma in config JSON → parser error line highlighted before deploy.
  • Large nested object → collapse sections mentally after pretty-print for code review.
  • Stripe webhook payload → pretty-print to inspect nested `data.object` fields.
  • package-lock fragment → validate structure before pasting into a bug report.

Common mistakes

  • Formatting JavaScript object literals with unquoted keys—they are not valid JSON.
  • Leaving BOM characters at file start from some exports.
  • Sharing formatted output containing live tokens or PII.

How it works

Paste JSON to format it with readable indentation or minify it into a single line. Invalid JSON shows a parse error with line and column when available. Optional key sorting orders object keys alphabetically. Formatting works on your device.

Limitations

Invalid JSON will not format until syntax errors are fixed. Very large documents may slow the browser tab.

Privacy and file handling

Your data stays on your device and is not uploaded.

Related JSON Formatter pages

These pages use the same json formatter with examples tailored to different tasks.

FAQ

Frequently asked questions

What is the difference between format and minify?

Format adds indentation for reading; minify removes whitespace for smaller wire size.

Does this validate JSON Schema?

Syntax validation is included; use the JSON schema generator or validator tools for schema checks.

Is there a size limit?

Very large files may slow the browser—split huge logs before formatting.

Related pages

Page last reviewed: