Paste or Type JSON
Enter your JSON in the input panel. The tool validates automatically as you type and highlights errors with exact line and column positions.
JSON Formatter
Format, validate, prettify, and minify JSON online. Features syntax highlighting, error position detection, collapsible tree view, and 100% in-browser privacy.
Your data stays in your browser.
JSON is processed locally and is not uploaded to DevPouch.
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Paste or type JSON. Validation runs automatically.
Awaiting input..."
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Formatted/minified JSON will appear here
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How to Format JSON
Choose an Action
Select indentation (2 spaces, 4 spaces, or tabs) and view mode (Text or Tree). Click Format to pretty-print, Minify to compress, or Validate to check syntax.
Copy or Download
Review the output with syntax highlighting or explore the collapsible tree view. Copy to clipboard or download as a .json file. Your original input is never modified.
JSON Syntax Rules & Common Errors
✓ Valid JSON Requirements
- Data must be an object
{...}or array[...] - Keys must be double-quoted strings:
{"key": "value"} - Strings must use double quotes:
"text"(not single quotes) - No trailing commas after the last item in objects/arrays
- Numbers must not have leading zeros:
0.5not.5 - Only these literals:
true,false,null(lowercase)
✗ Common Errors
| Error | Wrong | Correct |
|---|---|---|
| Trailing comma | {"a":1,} | {"a":1} |
| Single quotes | {'a':1} | {"a":1} |
| Unquoted keys | {a:1} | {"a":1} |
| Leading zero | {"n":01} | {"n":1} |
| Comments | {//comment} | {} (JSON has no comments) |
| Undefined/NaN | {"x":NaN} | {"x":null} |
Code Snippets: JSON in Popular Languages
// Parse JSON string
const data = JSON.parse(jsonString);
// Stringify with pretty print (2 spaces)
const pretty = JSON.stringify(obj, null, 2);
// Minify (compact)
const compact = JSON.stringify(obj);import json
# Parse JSON string
data = json.loads(json_string)
# Pretty print (2 spaces indent)
pretty = json.dumps(obj, indent=2)
# Minify (no whitespace)
compact = json.dumps(obj, separators=(',', ':'))import "encoding/json"
// Parse JSON
var data map[string]interface{}
json.Unmarshal([]byte(jsonStr), &data)
// Pretty print
pretty, _ := json.MarshalIndent(obj, "", " ")
// Minify
compact, _ := json.Marshal(obj)<?php
// Parse JSON
$data = json_decode($jsonString, true);
// Pretty print (PHP 5.4+)
$pretty = json_encode($obj, JSON_PRETTY_PRINT);
// Minify
$compact = json_encode($obj);?>Frequently Asked Questions
- No. All processing happens entirely in your browser. Your JSON data never leaves your device.
- Formatting (pretty-print) adds indentation and line breaks for readability. Minifying removes all unnecessary whitespace to reduce file size.
- Yes, up to the memory limits of your browser (typically hundreds of MB). For very large files, consider using a streaming parser.
- Yes. The tool validates JSON in real-time and shows error position (line, column) with a helpful snippet.
- Yes. Use the Download button to save the result as a .json file.
- No. The tool creates a formatted/minified copy. Your original input remains unchanged.
- Once the page is loaded, the tool works offline because all logic runs client-side.
- The tool supports 2 spaces, 4 spaces, and tab indentation for formatted output.
- Yes. The collapsible tree view lets you expand/collapse objects and arrays for easy navigation of complex JSON structures.
Use Cases
JSON is the standard data format for modern web APIs, configuration files, and data exchange between services. Working with raw, minified, or invalid JSON slows down development and increases the risk of production errors. The JSON Formatter & Validator helps developers beautify, validate, minify, and inspect JSON quickly and securely.
Developers who consume REST or GraphQL APIs frequently receive minified JSON responses compressed into a single line, which is nearly impossible to read or debug by eye. The JSON Formatter & Validator beautifies these payloads into clean, consistently indented structures, making nested objects, arrays, and key-value pairs easy to scan and understand at a glance.
Quality assurance teams can validate JSON syntax before pushing configuration files or API contracts to production. The tool catches missing commas, unmatched brackets, trailing commas, invalid quotes, and other malformed syntax locally, preventing broken parsers, failed deployments, and hours of unnecessary debugging downstream.
Frontend engineers optimizing network performance use the minify function to compress JSON data by stripping unnecessary whitespace, line breaks, and indentation. This reduces payload size for faster transfers across web applications and mobile clients without altering the underlying data or breaking validity.
Security reviewers inspect unfamiliar JSON structures for unexpected fields, deeply nested objects, or suspicious payloads before the data reaches backend services. The inspector reveals data types and structure so teams can verify content safely and reject malformed input early in the pipeline.
How-To
- Paste your raw JSON into the input editor, or upload a .json file directly from your computer.
- Click Beautify to format the document with consistent indentation and line breaks for easier reading.
- Click Validate to check syntax. The tool reports errors such as missing commas, invalid quotes, or unclosed brackets and highlights the exact line where the issue occurs.
- Click Minify to strip all unnecessary whitespace and produce a compact, single-line JSON string ready for transmission.
- Review the inspected output to confirm data types, nested objects, and array lengths match your expectations before copying the result.
- Copy the formatted, validated, or minified JSON to your clipboard and use it in API requests, configuration files, or application code.
The JSON Formatter & Validator processes everything in your browser, so no data is ever uploaded to external servers. Whether you need to beautify API responses, validate configuration files, minify payloads for production, or inspect complex JSON structures, this developer tool delivers fast, reliable results without compromising privacy or security.