What is JSON Formatter & Validator Online?
JSON (JavaScript Object Notation) is the universal data interchange format of the web. Raw JSON from APIs is often minified — no whitespace, compact — making it unreadable for humans. Our JSON formatter & validator online prettifies it with proper indentation, syntax highlighting, and immediate validation so you can spot errors at a glance. This tool is indispensable for web developers working with REST APIs, GraphQL, or configuration files. It instantly detects common syntax errors like trailing commas, missing quotes, or mismatched braces, pointing out the exact line where the error occurred. Because all processing happens in your browser, your data remains private. We never send your JSON to any server. This makes it a safe tool for inspecting payloads containing sensitive data or large datasets that would slow down server-side formatters.
How to Use JSON Formatter & Validator Online
- Paste your raw JSON into the input area.
- The formatter validates and prettifies it instantly.
- If invalid, the error message pinpoints the exact position of the syntax error.
- Use the Minify button to compact JSON for transmission.
Example
Prettified JSON output
Input
{"name":"John","age":30}Output
{
"name": "John",
"age": 30
}Developer Tips
Use the "Minify" feature before sending JSON in a production API request to reduce payload size. For local debugging, always use the 2-space indentation standard for maximum readability.
Frequently Asked Questions
Why is my JSON invalid?
Common JSON errors: trailing commas (not allowed in JSON), single quotes (must use double), unquoted keys, and undefined/NaN values (not valid JSON types).
What is the difference between JSON and YAML?
JSON is strict, machine-friendly, and widely supported. YAML is more human-readable, supports comments, and is commonly used for configuration files.