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JSON Formatter

HomeToolsDeveloperJSON Formatter

Automatically format and validate JSON in your browser.

  • No signup
  • Local-first
  • Free limit: Text input

Preparing the editor...

The guide and instructions on this page are available while the tool loads.

Continue your workflow

  • Decode JWTInspect token claims.
  • Minify codeCompact code output.
  • Compare textReview changes.

If parsing succeeds, the tool reformats the content using clear indentation. If parsing fails, the JSON likely contains syntax issues such as missing commas, invalid quotes, or mismatched brackets.

Because processing happens locally in the browser, you can inspect sensitive payloads without sending them to an external server.

Common uses for JSON Formatter

Typical tasks this tool is built for.

  • Validate API responses during development.
  • Format large JSON payloads for easier reading.
  • Catch syntax errors before using configuration files.
  • Inspect structured data before copying it into documentation.

How to use JSON Formatter

  1. Step 1. Paste raw JSON into the input area.
  2. Step 2. Wait for parsing, validation, and formatting to update automatically; there is no manual Format button.
  3. Step 3. Choose 2, 4, or 8 spaces from the Indent control.
  4. Step 4. Read the formatted output when JSON.parse succeeds.
  5. Step 5. If parsing fails, use the displayed browser parser message to locate the syntax issue.
  6. Step 6. Keep the input at or below 1,000,000 characters before trying again.

Why use this tool?

  • Parse JSON with JSON.parse and show the browser parser message when the input cannot be parsed.
  • Pretty-print valid objects and arrays with JSON.stringify after each input or indentation change.
  • Choose 2, 4, or 8 spaces for the formatted output.
  • See the current input character count while preparing API payloads or configuration text.
  • Reject processing once input exceeds the implemented 1,000,000-character limit.

Privacy and formats

Formatting and validation run locally in your browser. JSON payloads are not sent to a server for this task.

Input: TextOutput: Processed text

Best results with JSON Formatter

Practical tips before you download or share the output.

JSON requires double quotes for keys and strings, and does not allow trailing commas.

Related guides

Longer reads that pair well with this tool.

Developer guide

Useful Developer Tools Every Browser Should Have

Fourteen In-browser developer utilities for JSON, encoding, tokens, diffs, hashes, regex, SQL, UUIDs, and timestamps — fast checks without installing anything.

Developer guide

How to Format JSON Online

Use automatic JSON.parse and JSON.stringify formatting, inspect strict-JSON parser errors, and review indented text up to 1,000,000 characters.

Developer guide

How to Redact and Review Sensitive JSON

Reduce exposure while reviewing sensitive JSON by using synthetic data, redacting credentials and identifiers, and checking browser, screen, and clipboard risks.

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Common problems this tool helps with

Situations where this workflow saves time.

Trailing commas — JSON does not allow them; remove the last comma in arrays or objects.
Single quotes — JSON requires double quotes for keys and strings.
Unquoted keys — object property names must be enclosed in double quotes.
Comments — JSON.parse rejects // and /* */ comments even when JavaScript would accept nearby syntax.
Broken strings or escapes — unescaped newlines and invalid backslash sequences prevent parsing.
Missing brackets or braces — an incomplete array or object leaves no formatted result.
Input over 1,000,000 characters — the tool reports a size error instead of processing it.
Expecting a minify, copy, or download action — this component only shows automatic pretty-printed output.

Frequently asked questions

Does JSON Formatter need a Format button?

No. Input changes and indentation changes trigger the parse, validation, and pretty-printing work automatically.

Which parser and formatter does it use?

It parses with JSON.parse and serializes valid values with JSON.stringify using the selected indentation amount.

Which indentation amounts are available?

The selector offers 2, 4, and 8 spaces. Changing it updates the formatted output automatically.

What is the input limit?

The component accepts up to 1,000,000 characters. Larger input shows a size error and is not processed.

Why does JSON that works in JavaScript fail here?

JSON is stricter: it does not allow comments, trailing commas, single-quoted strings, or unquoted property names.

Does the tool make minified JSON?

No. It produces pretty-printed JSON only. Already-minified input can become readable after a successful parse.

Can I sort object keys?

No key-sorting option is implemented. The component parses and serializes the value without a sorting control.

Can I copy or download the formatted output?

No copy or download control is implemented in this formatter.

Does it provide line-and-column error pointers?

The component displays the browser parser message. It does not add a separate guaranteed line-and-column error interface.

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