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Format, validate, and beautify JSON instantly in your browser. Free, private — all processing in your browser.

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Paste minified or messy JSON and get it back cleanly indented and validated — or go the other way and minify it for transport. When something's wrong, the tool points at the problem (it reports the position of the first parse error) instead of just saying "invalid." Alongside the formatted output it shows quick stats: the top-level type, key and value counts, nesting depth, and byte size, so you get a feel for the shape of the data at a glance.

There's an optional sort keys mode (alphabetize keys at every level, useful for diffing two JSON blobs), a choice of 2-space, 4-space, or tab indentation, and one-click minify. It all runs in your browser — a config or API payload you paste never touches a server.

How to use the JSON Formatter

  1. 1

    Paste your JSON

    Copy your JSON from an API response, config file, log, or database query and paste it into the input area. You can also drag and drop a .json file.

  2. 2

    Choose an action

    Click Format (Pretty Print) to get indented, readable output. Click Minify to get compact output with no whitespace. Click Validate to check syntax without changing the format.

  3. 3

    Review the output

    Formatted JSON appears instantly. If the input is invalid, you will see a precise error message with the line and column of the syntax problem.

  4. 4

    Use the tree view

    For large JSON, switch to tree view to explore nested structure. Click any object or array to expand or collapse it.

  5. 5

    Copy or download

    Click the Copy button to copy the formatted JSON to your clipboard. Or click Download to save it as a .json file.

  6. 6

    Fix errors if needed

    If the validator reports an error, the tool shows the exact location. Common fixes include adding missing commas, removing trailing commas, wrapping keys in double quotes, and escaping special characters in strings.

JSON Formatter — examples

Format minified JSON

Typical API response comes minified. The formatter transforms it into readable, indented JSON.

Input
{"user":{"id":42,"name":"Ada Lovelace","email":"ada@example.com","roles":["admin","engineer"],"profile":{"bio":"Analytical Engine pioneer","active":true}}}
Output
{
  "user": {
    "id": 42,
    "name": "Ada Lovelace",
    "email": "ada@example.com",
    "roles": [
      "admin",
      "engineer"
    ],
    "profile": {
      "bio": "Analytical Engine pioneer",
      "active": true
    }
  }
}

Minify formatted JSON

Compact indented JSON to remove whitespace — useful for URLs, HTTP headers, or minimizing payload size.

Input
{
  "name": "Tooleras",
  "tools": 235,
  "free": true
}
Output
{"name":"Tooleras","tools":235,"free":true}

Detect a syntax error

Missing comma between properties is one of the most common JSON mistakes.

Input
{
  "status": "active"
  "count": 10
}
Output
SyntaxError: Expected comma or closing brace at line 3, column 3

Format an array of objects

Arrays of objects are typical in API list endpoints (users, products, posts).

Input
[{"id":1,"title":"Hello"},{"id":2,"title":"World"}]
Output
[
  {
    "id": 1,
    "title": "Hello"
  },
  {
    "id": 2,
    "title": "World"
  }
]

Handle escaped characters

Quotes, newlines, and Unicode inside strings must be properly escaped.

Input
{"message":"She said \"hello\"\nNew line here","symbol":"\u2603"}
Output
{
  "message": "She said \"hello\"\nNew line here",
  "symbol": "☃"
}

Features at a glance

Instant pretty print with indentation

Format JSON with 2, 4, or 8-space indentation. Nested objects and arrays are indented correctly, making deeply-nested structures readable at a glance.

Real-time validation

JSON is validated as you type. Invalid syntax is detected immediately with a clear error message pointing to the line and character of the problem.

Minify JSON

Compact JSON by removing all unnecessary whitespace. Useful for reducing API payload size, embedding JSON in URLs, or saving storage space.

Tree view for navigation

Collapse and expand nested objects and arrays. Essential for exploring large API responses with dozens of nested levels without scrolling through thousands of lines.

Syntax highlighting

Keys, strings, numbers, booleans, and null values are color-coded in the output for faster scanning and error spotting.

Copy, download, and share

Copy the formatted output to clipboard with one click, or download it as a .json file for use in your codebase or as a test fixture.

Handles JSON of any size

Works with small config files, large API responses, and multi-megabyte data dumps. Processing speed is limited only by your browser memory.

100% client-side processing

Your JSON never leaves your browser. No server uploads, no logging, no third-party analytics on the content. Safe for API keys, tokens, and sensitive data.

When to use the JSON Formatter

Web development and APIs

  • →Debug REST API responses: Paste the raw JSON response from Postman, Insomnia, curl, or browser DevTools to read the structure clearly.
  • →Inspect webhook payloads: Stripe, GitHub, Slack, and other webhook providers send JSON payloads — format them to understand what each field means.
  • →Test API request bodies: Build and validate JSON bodies for POST, PUT, and PATCH requests before sending.
  • →Parse GraphQL responses: GraphQL returns deeply nested JSON — the tree view makes it easy to navigate query results.

Configuration and DevOps

  • →Format package.json: Clean up the package.json file in your Node.js project, especially after automated changes by tools like npm or yarn.
  • →Validate tsconfig.json, eslintrc, prettierrc: These config files are JSON — formatting them keeps diffs small and readable.
  • →Inspect Kubernetes manifests: When Kubernetes outputs JSON (kubectl get pod -o json), format it to read pod specs and statuses.
  • →Debug AWS CloudFormation or Terraform state: Format state files to understand what infrastructure exists and what changed.

Data analysis and ETL

  • →Explore NoSQL documents: MongoDB, DynamoDB, Firestore, and CouchDB store documents as JSON — format them to read their structure.
  • →Convert logs to readable format: Structured logs from services like Datadog, Splunk, or Elastic are JSON lines — pretty print them for debugging.
  • →Prepare data fixtures: Format test JSON fixtures consistently so diffs are meaningful in version control.

Learning and documentation

  • →Teach JSON syntax: Use the formatter to show students the difference between valid and invalid JSON.
  • →Document API contracts: Format example request/response pairs for API documentation pages.

Under the hood

What formatting actually changes: nothing that matters. Beautifying and minifying only add or remove insignificant whitespace. The data — keys, values, order, types — is identical. {"a":1} and the same object across five indented lines are the same JSON. So formatting is always safe; it's purely for human readability or transport size.

Validation is strict, on purpose. The tool parses with the real JSON grammar (JSON.parse), so it rejects the things that *look* like JSON but aren't: trailing commas, single-quoted strings, unquoted keys, comments, NaN/Infinity. That strictness is a feature — if it parses here, it'll parse in any conformant system.

Sort keys = canonical form. Alphabetizing keys at every level gives JSON a stable, canonical shape. That's what makes two payloads actually diffable: without it, the same data with keys in a different order looks "changed."

A number gotcha. JSON numbers are parsed as JavaScript doubles, so integers beyond 2^53 (big IDs, snowflake IDs) can silently lose precision. If you're handling huge integers, keep them as strings in the JSON.

Common problems and solutions

⚠Trailing comma after the last item

Valid in JavaScript, invalid in JSON. {"a":1,} fails. Remove the trailing comma — the error position points you right at it.

⚠Single quotes instead of double quotes

JSON requires double quotes for both keys and string values. 'text' and {key:1} are not valid JSON; use "text" and {"key":1}.

⚠Comments in the file

Strict JSON has no comments. If your file uses // or /* */, it's JSON5/JSONC — strip the comments or use a JSON5 parser. This validator rejects them on purpose.

⚠Large integers losing precision

JSON numbers are parsed as 64-bit floats, so IDs above ~9 quadrillion (2^53) can change value. Store very large integers as strings to keep them exact.

⚠Duplicate keys silently collapsing

If an object repeats a key, parsers keep only the last one. That's valid JSON but usually a mistake — check for accidental duplicates when data goes missing.

How it compares

Format vs minify. Same data, opposite goals: formatting adds whitespace for reading and code review; minifying strips it for smaller payloads over the wire. Use formatted in your editor and logs, minified in production responses.

This vs a dedicated JSON validator. They overlap — this formatter validates too and shows *where* an error is. A pure JSON Validator is for when you only want the pass/fail and error location without reformatting.

JSON vs JSON5 / JSONC. JSON5 and JSONC allow comments, trailing commas, and unquoted keys — convenient for config files. Strict JSON (what APIs use, and what this validates) allows none of that. If your file has comments, it's JSONC, not JSON, and it will fail here by design.

Formatting vs converting. If you actually need the data in another shape, use a converter — e.g. JSON to YAML or CSV to JSON — rather than the formatter.

JSON Formatter — FAQ

▶Is my JSON uploaded anywhere?

No. Parsing, formatting, and validation all happen in your browser. Nothing is sent to a server, so it's safe for private configs and API payloads.

▶Why does my JSON show as invalid?

Almost always a trailing comma, single quotes, an unquoted key, or a comment — none of which are legal in strict JSON. The tool reports the position of the first error so you can jump straight to it.

▶Does formatting change my data?

No. Beautify and minify only add or remove whitespace. Keys, values, order, and types stay identical — it's purely about readability versus size.

▶What does sort keys do and when should I use it?

It alphabetizes object keys at every level, giving the JSON a stable canonical form. Use it before diffing two payloads so key ordering differences don't show up as false changes.

▶Should I minify for production?

Usually yes for API responses and payloads — smaller means faster over the network. Keep formatted JSON for logs, config, and anything a human reads.

▶Can it handle large JSON files?

It works entirely in your browser's memory, so it handles sizeable files fine, but multi-hundred-megabyte inputs can get sluggish. For those, a streaming/CLI tool like jq is the better fit.

Additional resources

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