JSON Formatter & Validator
Free online JSON formatter and validator. Format, minify, and validate JSON with an interactive tree view — collapse nodes, delete keys or array items, syntax highlighting, precise error messages. Fully client-side.
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What is JSON
JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy for humans to read and write, and easy for machines to parse and generate. It has become the de facto standard for modern Web APIs, used by RESTful services, configuration files, and data stores worldwide. Common JSON data types include strings, numbers, booleans, null, arrays, and objects.
When do you need to format JSON
When API responses return compressed single-line strings, they are nearly impossible to read. Formatting JSON adds indentation and line breaks, making the data structure immediately clear. You'll need a JSON formatter when debugging API endpoints, reviewing log files, auditing configuration files, or performing data migrations. Formatted JSON also makes it easier to spot syntax errors like missing commas or mismatched quotes.
Online JSON tools vs editor plugins
VS Code, Sublime Text, and other editors have JSON formatting plugins that work well during development. But for quick debugging, cross-device work, or sharing with non-technical team members, online JSON tools are more convenient — no installation required, just open your browser. Our tool supports an interactive tree view where you can collapse/expand nodes and delete keys, more intuitive than plain text editing.
JSON in Your Language
// Parse JSON string
const obj = JSON.parse('{"name":"Alice","age":30}');
// Format with 2-space indent
const pretty = JSON.stringify(obj, null, 2);
// Minify
const mini = JSON.stringify(obj);import json
# Parse
obj = json.loads('{"name": "Alice", "age": 30}')
# Format
pretty = json.dumps(obj, indent=2, ensure_ascii=False)
# Minify
mini = json.dumps(obj, separators=(',', ':'))import ( "encoding/json" "bytes" ) // Format var buf bytes.Buffer json.Indent(&buf, raw, "", " ") // Minify var mini bytes.Buffer json.Compact(&mini, raw)
use serde_json::Value; // Parse and format let v: Value = serde_json::from_str(raw)?; let pretty = serde_json::to_string_pretty(&v)?; // Minify let mini = serde_json::to_string(&v)?;
Frequently Asked Questions
- What is JSON?
- JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy for humans to read and write, and easy for machines to parse and generate. It is language-independent and widely used in APIs, config files, and data storage.
- Why format JSON?
- Raw JSON is often compact — no whitespace, no line breaks — which is efficient for transmission but hard to read. Formatting (beautifying) adds indentation and newlines to reveal the structure at a glance, making it much easier to debug and inspect data.
- How do I validate JSON?
- Valid JSON requires: strings in double quotes, keys as strings, matched brackets, no trailing commas, and no comments. This tool parses your input in real time and shows precise error messages if something is wrong.
- What is the difference between JSON and a JavaScript object?
- JSON is plain text — keys must be double-quoted, no functions, no undefined, no comments, no trailing commas. A JavaScript object is an in-memory data structure where keys can be unquoted identifiers and values can be functions or Symbols.
- Why minify JSON?
- Minifying removes all unnecessary whitespace, shrinking the file size and speeding up network transfers. It is commonly used for production API responses and deployed config files.
- How does the interactive tree view work? Can I edit the JSON?
- After formatting, the output renders as an interactive tree. Click the chevron next to any object or array to collapse or expand it. Hover any row to reveal a × button on the right — clicking it deletes that key-value pair or array item. Edits only affect the output; the original input is untouched, so you can always re-parse it.