JSON Formatter

Format, validate, and inspect JSON with browser-side tooling that goes beyond pretty-printing. This page is designed for API debugging, schema checks, and spotting structural errors fast.

Last updated: March 25, 2026

Used 94K+ times

Client-Side Processing

Input Data Stays on Device

Instant Local Execution

What users say

“Finally a JSON formatter that doesn't send my API keys to some random server. The real-time formatting is incredibly fast — better than anything I've tried in VS Code.”

Priya S. — Frontend Developer

“I paste API responses here daily. The tree view toggle makes deeply nested objects so much easier to navigate during debugging.”

Marcus T. — Backend Engineer

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What is JSON Formatter?

JSON (JavaScript Object Notation) is a lightweight data interchange format used everywhere — from REST APIs to config files. Our JSON Formatter transforms messy, minified, or unreadable JSON into properly indented, easy-to-read format.

It also validates your JSON and tells you the **exact line and column** where the error is, along with a plain-English tip on how to fix it. Need to go deeper? Switch to **Tree View** to explore nested structures visually, use **Diff** to compare two JSON objects, or paste a **JSON Schema** to validate your data structure. All processing runs 100% in your browser — your JSON never leaves your device.

How to Use JSON Formatter

Paste your JSON into the input box (or click a **Sample** button to load a ready example)

Click **Format** to beautify it, or **Minify** to compress into one line

Click **Validate** to check if it's valid — errors show the exact line, column, and a fix tip

Adjust **Indent** (2 spaces / 4 spaces / Tab) and toggle **Sort keys** as needed

Enable **Auto-fix issues** to automatically correct trailing commas, single quotes, and unquoted keys

Switch to the **Tree View** tab to explore nested JSON visually — hover any key to copy its JSONPath

Switch to **⇄ Diff** tab to compare two JSON objects side-by-side with color-coded changes

Switch to **✔ Schema** tab to validate your JSON against a JSON Schema (Draft 7)

Click **Copy** to copy the result, or **Download** to save as a `.json` file

Common Use Cases

Debugging API responses during development
Formatting config files for better readability
Validating JSON before sending it to an API endpoint
Minifying JSON to reduce payload size in production
Sorting keys alphabetically for consistent, diff-friendly output
Comparing two API responses to identify what changed
Validating a JSON payload against a contract schema
Exploring deeply nested JSON structures in Tree View
Auto-fixing common JSON mistakes before parsing

Example Input and Output

The formatter keeps the data identical while making nested API payloads far easier to scan and debug.

Minified JSON

{"user":{"id":42,"email":"ops@example.com","roles":["admin","billing"],"flags":{"beta":true,"mfa":false}},"meta":{"requestId":"req_18a2","region":"ap-south-1"}}

Formatted JSON

{
  "user": {
    "id": 42,
    "email": "ops@example.com",
    "roles": [
      "admin",
      "billing"
    ],
    "flags": {
      "beta": true,
      "mfa": false
    }
  },
  "meta": {
    "requestId": "req_18a2",
    "region": "ap-south-1"
  }
}

Privacy

Formatting, validation, Tree View, Diff, and Schema checks run fully in the browser, which is useful when the payload contains internal API data.

Workflow tip

Use Format first, then switch to Tree View or Diff. It is much easier to inspect nested arrays and compare payload changes after the structure is normalized.

Large file tip

For JSON files larger than 1 MB, use the Tree View tab instead of scrolling the text editor. Tree View renders the structure lazily and is significantly faster to navigate for deeply nested payloads.

Frequently Asked Questions

What is JSON?

JSON (JavaScript Object Notation) is a lightweight data format used to exchange data between applications and servers. It is based on key-value pairs and supports types: string, number, boolean, null, array, and object.

What makes JSON valid?

Valid JSON uses double quotes for all strings and keys, has no trailing commas, and contains only supported types: string, number, boolean, null, array, and object. Keys must always be strings.

Why does JSON require double quotes?

JSON is a strict standard (RFC 8259). Single quotes are common in JavaScript but are not valid JSON. Use double quotes for all keys and string values.

What is a trailing comma?

An extra comma after the last item in an object or array — e.g. {"a": 1,}. JSON does not allow trailing commas, but JavaScript does. Enable "Auto-fix issues" to remove them automatically.

My JSON is valid in JavaScript but invalid here — why?

JavaScript allows things JSON does not: unquoted keys, single quotes, trailing commas, and undefined. This tool checks strict JSON (RFC 8259) rules. Use the "Auto-fix issues" toggle to convert JS-style objects to valid JSON.

Is my JSON data safe?

Yes. All formatting, validation, diff, and schema checking runs entirely in your browser. Your JSON is never uploaded to any server.

Can I format large JSON files?

Yes. Most JSON files up to several MB will work fine. Very large files (10MB+) may be slow in older browsers. The Tree View is especially useful for navigating large JSON without having to scroll thousands of lines.

Does formatting change my data?

No. Formatting only changes whitespace and indentation — values, types, and structure remain identical. If you enable "Auto-fix issues", the tool may rewrite quotes and remove commas, which it will clearly notify you about.

Can I download the formatted JSON?

Yes. Click the "Download .json" button below the result to save the formatted output as a file.

How does the JSON Diff feature work?

After formatting your first JSON, switch to the "⇄ Diff" tab and paste a second JSON. The tool will compare them recursively and highlight added keys (green), removed keys (red), and changed values (amber), including a summary count at the top.

How does JSON Schema validation work?

Switch to the "✔ Schema" tab and paste a JSON Schema (Draft 7 format). Click "Validate against schema" and the tool will check your JSON for required fields, type mismatches, min/max values, and more. Each violation is shown with its exact key path.

Can this tool convert JSON to YAML or CSV?

This tool is focused on formatting, validating, and comparing JSON. For conversions, check our related tools: JSON to YAML Converter and JSON to CSV Converter.

What is JSONPath and how do I use it here?

JSONPath is a query language for navigating JSON structures, similar to XPath for XML. In Tree View, hover any key to see its JSONPath (e.g. $.user.roles[0]). You can copy the path directly to use in code with libraries like jsonpath-plus or jq.

What are the most common JSON errors and how do I fix them?

The 5 most common JSON errors are: (1) Trailing comma — remove the comma after the last item in an object or array. (2) Single quotes — replace all single quotes with double quotes. (3) Unquoted keys — wrap object keys in double quotes. (4) undefined value — JSON does not support undefined; replace with null. (5) Comments — JSON does not allow // or /* */ comments; remove them. Enable "Auto-fix issues" and this tool will automatically correct the first three.

How This Tool Works

Your JSON is parsed using the browser's native JSON.parse() engine with a custom pre-processor that detects and optionally fixes common deviations (trailing commas, single quotes, unquoted keys). Validation, Tree View, Diff, and Schema checks all run synchronously in the main thread — no data is ever sent to a server.

Technical Stack

JSON.parse (native)Ajv (JSON Schema Draft 7)Web WorkersClient-side only