Instantly validate JSON syntax, auto-format messy JSON with proper indentation, and identify errors. Minify and beautify JSON. 100% private, browser-based.
Paste your JSON into the input panel.
Click "Validate" to check syntax — errors shown with line numbers.
Click "Format" to beautify with proper 2-space indentation.
Click "Minify" to compress JSON by removing all whitespace.
Copy the output to your clipboard.
Common mistakes include trailing commas, unquoted keys, single-quoted strings, and using undefined as a value. Our validator pinpoints the exact error location.
Yes. All processing is 100% client-side in your browser. Your JSON data never leaves your device.
Formatting adds indentation and line breaks for human readability. Minifying removes all unnecessary whitespace for smaller file sizes in production.
JSON (JavaScript Object Notation) has quietly become the lingua franca of the modern web. REST APIs, configuration files, database documents, webhooks, analytics event streams — they all speak JSON. And JSON is deceptively easy to break.
A single misplaced comma, an unquoted key, or a trailing bracket can silently corrupt your data exchange. Unlike HTML, which browsers try to recover from, a JSON parser will simply throw an error and return nothing. Your application breaks, your UI shows nothing, and debugging starts from scratch.
Our JSON Validator instantly tells you whether your JSON is syntactically valid — and if it isn't, it points to the exact location of the error.
Understanding JSON's strict rules helps you write it correctly from the start:
Keys must be double-quoted strings. {name: "Alice"} is not valid JSON — {"name": "Alice"} is.
No trailing commas. Many languages allow trailing commas in arrays and objects; JSON doesn't. [1, 2, 3,] causes a parse error.
Strings must use double quotes. Single quotes (') are not valid JSON string delimiters.
Numbers cannot have leading zeros. 007 is not valid; 7 is.
undefined is not a valid value. Only null, booleans, numbers, strings, arrays, and objects are valid JSON values.
No comments. JSON doesn't support // or /* */ comments, despite how readable they'd make config files.
When you paste valid JSON into the formatter, it processes your code through these steps:
JSON.parse().JSON.stringify(obj, null, 2) re-serializes the object with 2-space indentation, proper line breaks, and consistent key ordering within each level.The result is clean, consistently indented JSON that a human can actually read and navigate.
The reverse operation — minifying — strips all whitespace and newlines to produce the most compact representation. A formatted 10KB JSON file might minify down to 3KB. This matters for:
Looking for a more detailed deep-dive and advanced tips?
Read Full Article on our BlogYour data never leaves this device. All processing is handled locally by JavaScript.
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