Format, validate, minify, and visualize JSON data instantly. Tree view, error detection, and customizable indentation — no signup required.
{
"name": "Tech System Lab",
"version": "2.0.0",
"features": [
"tools",
"blog",
"pdf-tools"
],
"config": {
"theme": "dark",
"language": "en",
"notifications": {
"email": true,
"push": false
}
},
"users": [
{
"id": 1,
"name": "Alice",
"role": "admin"
},
{
"id": 2,
"name": "Bob",
"role": "editor"
}
]
}JSON Formatter is a free, browser-based tool that pretty-prints, validates, and minifies JSON while giving you a collapsible tree view of the structure. Paste raw JSON from an API response, a config file, a log line, or a database export, and it reindents the text with consistent spacing, flags syntax errors, and lets you drill into nested objects and arrays.
It is built for developers, QA engineers, and data analysts who work with REST APIs, webhook payloads, NoSQL documents, and application config. Because everything runs locally in your browser, it handles sensitive request bodies and tokens without ever uploading them to a server.
The tool parses your input using a strict JSON parser that follows the RFC 8259 specification. Valid JSON allows six value types: objects (wrapped in curly braces), arrays (wrapped in square brackets), strings (in double quotes), numbers, the booleans true and false, and null. Keys must be double-quoted strings, and trailing commas are not permitted. If the parser cannot build a valid structure, it stops and reports the failure point so you can fix the offending character.
Formatting is a two-stage process: the raw text is parsed into an in-memory data structure, then serialized back out with consistent indentation and line breaks. This means the output is semantically identical to the input but visually organized, and it also normalizes inconsistent spacing or escaping. Minifying runs the same parse step and then serializes with no whitespace, which is why a valid but ugly payload and its minified version are interchangeable to any consumer.
Because the parse-then-serialize round trip requires strictly valid JSON, the formatter doubles as a validator. Common issues it catches include single quotes instead of double quotes, unquoted keys, trailing commas, missing closing brackets, and unescaped control characters inside strings.
Yes, it is completely free with no sign-up required. All formatting, validation, and minifying happen in your browser using JavaScript, so your JSON is never uploaded to or stored on any server.
The most common causes are single quotes instead of double quotes around keys or strings, trailing commas after the last element, unquoted keys, or a missing closing bracket or brace. Strict JSON also does not allow comments, so remove any // or /* */ sections.
Format adds indentation and line breaks so the structure is readable, while Minify removes all unnecessary whitespace to produce the smallest single-line output. Both keep the data identical; only the presentation changes.
It can handle sizable payloads since processing is local, but very large files (tens of megabytes) may be limited by your browser's memory and can slow down the tree rendering. For extremely large data, minifying first or splitting the file helps.
No. The tool validates against standard JSON (RFC 8259), which does not allow comments, trailing commas, or unquoted keys. If your source uses those, remove them before formatting.
No. Formatting and minifying only adjust whitespace and line breaks. Key order, values, and structure are preserved exactly, so the output is functionally equivalent to the input.
Yes. The tree view lets you expand and collapse individual objects and arrays, so you can focus on one branch of a nested response without scrolling through the entire document.