JSON Validator & Formatter
Validate, format, minify, and explore JSON data instantly — with error detection, tree view, and JSON path display. All in your browser.
String: "hello"
Number: 42, 3.14
Boolean: true, false
null
Object: { "key": value }
Array: [1, 2, 3]
Nested: { "a": [1] }
\\" — double quote
\\\\ — backslash
\\n \\t — newline, tab
\\uXXXX — unicode
Trailing commas
Single quotes
Unquoted keys
Comments
JSON.parse(str)
JSON.stringify(obj)
JSON.stringify(o,null,2)
Spec: no size limit
Nesting: unlimited
Numbers: IEEE 754
What is JSON?
JSON (JavaScript Object Notation) is a lightweight data interchange format defined by ECMA-404 and RFC 8259. It uses human-readable text to store and transmit data objects consisting of key-value pairs and arrays. JSON is the dominant format for REST APIs, configuration files, and data exchange between web services.
Why Validate JSON?
- Catch syntax errors early: A missing comma or mismatched bracket can break an entire API request or config file. Validation catches these before they cause runtime failures.
- Debug API responses: When an API returns unexpected data, validating and formatting the response reveals structural issues instantly.
- Clean configuration files: Many tools (package.json, tsconfig.json, Docker Compose) use JSON configs — validation prevents deployment errors.
- Data pipeline integrity: Before ingesting JSON data into databases or processing pipelines, validation ensures the data conforms to expected structure.
JSON Formatting Options
| Option | Output | Best For |
|---|---|---|
| 2-space indent | Compact, readable | Most codebases, web projects |
| 4-space indent | Wide, very readable | Java/Python projects, documentation |
| Tab indent | Configurable width | Teams with mixed preferences |
| Minified | No whitespace | API payloads, production configs |
Frequently Asked Questions
What is a JSON validator?
A JSON validator checks whether a string is well-formed JSON according to the ECMA-404 / RFC 8259 specification. It verifies correct syntax including matching braces and brackets, proper use of commas and colons, valid string escaping, and correct data types. If the JSON is invalid, a good validator reports the exact line number and description of the error.
How do I format or prettify JSON?
Paste your JSON into the input area and click the Format button. You can choose between 2-space, 4-space, or tab indentation. The formatter parses the JSON and re-serializes it with consistent indentation and line breaks, making it easy to read and debug.
How do I minify JSON?
Paste your JSON and click the Minify button. This removes all unnecessary whitespace, newlines, and indentation from the JSON string, producing the most compact representation. Minified JSON is ideal for API payloads, configuration files, and reducing bandwidth.
What is a JSON path?
A JSON path is a string that describes the location of a specific value within a JSON document. For example, $.users[0].name refers to the name property of the first element in the users array. In this tool, clicking any value in the tree view displays its JSON path, which is useful for accessing nested data programmatically.
Can this tool fix invalid JSON?
Yes. The Fix Common Errors button attempts to repair frequently encountered JSON mistakes such as trailing commas after the last item in arrays or objects, single quotes instead of double quotes, unquoted property keys, and missing quotes around string values. While it cannot fix all errors, it handles the most common issues developers encounter.
What is JSON lint?
JSON lint (or JSONLint) refers to the process of validating and checking JSON data for syntax errors, similar to how a code linter checks source code. A JSON linter parses the input, reports any syntax errors with line numbers, and confirms whether the data is valid JSON. This tool acts as a full JSON linter with detailed error reporting.
Is my JSON data safe when using this tool?
Yes. All validation, formatting, and processing happens entirely in your browser using JavaScript. No data is sent to any server. Your JSON never leaves your device, making it safe for sensitive configuration files, API keys, and private data.
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