JSON Formatter & Validator

Format and validate your JSON safely in the browser without worrying about data leaks.

Raw Input

Formatted Output

Enter a valid JSON to display the formatted tree.

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📝 JSON Specifications & Guide to Syntax Validators

JSON (JavaScript Object Notation) is a lightweight, human-readable data interchange standard. Replacing bulky XML formats, it has established itself as the absolute standard for modern web API communication, configuration files, and application data processing.

🧩 Basic Rules and Properties of JSON Format

JSON enforces a strict syntax structure. Even a tiny typo can trigger a parsing error and halt program execution. Keep in mind the following three core rules: First, Key-Value Pairs are strict. Every key name in JSON must be enclosed in double quotes (`"key"`). Unlike JavaScript object literals, using single quotes (`'`) or omitting quotes entirely is treated as a major syntax violation. Second, exact Comma placement is required. Commas separate elements within objects or arrays, but trailing commas on the last item are strictly forbidden in standard specifications. Although some modern engines tolerate them, they are a primary cause of parsing failures in legacy environments. Third, there are data type constraints. Standard JSON only supports strings, numbers, booleans, nested objects, arrays, and null. It cannot serialize functions, undefined values, or raw expressions. Adding comments (`//` or `/* */`) will also break validation.

💡 How to Use the Local Formatter & FAQ

Q. Is it safe to paste confidential business JSON data into standard online tools? A. Utilizing random online tools to beautify your data during development is highly risky. Many web tools send your payload to backend servers, creating potential pathways for leaking API keys, customer databases, and proprietary variables. The JSON Formatter on EVEDAYS processes inputs 100% locally within your browser's memory. Since it never triggers network requests to outside databases, your corporate logs remain entirely private. Q. How do I pinpoint the cause of a JSON error? A. When syntax discrepancies are detected, a red exception warning displays at the bottom left. Review the line numbers and positions specified in the log to insert missing braces or replace illegal characters, and the syntax highlighter will render your structured data in real-time.