JSON Validator
Validate, format, and minify JSON data instantly. Check syntax errors and fix common issues.
Formatted Output
Introduction
A single missing comma, an unescaped quote, or a trailing comma in a JSON configuration file can bring down an entire application at startup. JSON parsers produce notoriously unhelpful error messages like "Unexpected token at position 847" with no indication of what is wrong or where the actual mistake lies. A JSON validator not only tells you whether your JSON is syntactically correct but pinpoints the exact line and character where the error occurs, turning a frustrating debugging session into a quick fix.
What Is JSON Validator?
A JSON validator parses your JSON string and reports whether it conforms to the RFC 8259 specification. When parsing succeeds, the validator formats and pretty-prints the JSON with configurable indentation (2 spaces, 4 spaces, or tabs) and validates it against an optional JSON Schema definition. When parsing fails, it highlights the exact error position with a visual marker and provides a plain-language explanation such as "Trailing comma after the last property in an object is not allowed in JSON."
The validator catches the most common JSON mistakes that developers encounter: trailing commas (allowed in JavaScript but forbidden in JSON), single quotes instead of double quotes, unquoted object keys, comments (not allowed in standard JSON), and missing commas between array or object elements. Each error is classified by type and severity, making it easy to distinguish between a hard syntax error that will break parsing and a style issue that makes the JSON harder to maintain.
For advanced validation, the tool supports JSON Schema (Draft 07 and Draft 2020-12) checking. You provide a schema alongside the JSON instance, and the validator reports any violations such as missing required properties, values outside allowed ranges, strings that do not match regex patterns, or additional properties not defined in the schema. This is invaluable for API developers who want to validate request payloads against their OpenAPI specifications without writing custom validation code.
JSON Validator Examples
| Input | Output |
|---|---|
| {"name": "Alice", "age": 30,} | Error: Trailing comma at line 1, column 29 — remove comma before closing brace |
| {'name': 'Alice'} | Error: Single quotes at line 1, column 2 — JSON requires double quotes |
| {"name": "Alice", "age": 30} | Valid JSON — formatted with 2-space indentation, schema check passed |
Key Features of JSON Validator
- RFC 8259 compliant validation with precise line and column error reporting for invalid JSON
- Plain-language error explanations for common mistakes like trailing commas, single quotes, and unquoted keys
- Automatic pretty-printing with configurable indentation (2 spaces, 4 spaces, or tabs)
- JSON Schema validation (Draft 07 and Draft 2020-12) for structural and type checking against a schema definition
- Error categorization by type and severity to distinguish syntax errors from style warnings
- Minification mode that strips all whitespace to produce the most compact valid JSON representation
- Key path display that shows the full object path to any error location for navigating deeply nested structures
How It Works
Paste Your JSON String
Enter the JSON text you want to validate into the input area. The validator accepts raw JSON from API responses, configuration files, environment variables, or any other source where you need to confirm the syntax is correct before processing the data further.
Syntax Validation with Error Location
The tool attempts to parse your JSON and reports whether it is valid or invalid. When errors are found, the validator identifies the specific line number and column position where the problem occurs, along with a description of what went wrong such as a missing comma, unclosed bracket, or unexpected token.
Fix Errors and Validate Again
Use the line and column information to locate the error in your JSON, fix it, and re-validate until the tool confirms your JSON is syntactically correct. The instant feedback loop lets you iterate through corrections quickly without deploying code to find parsing errors.
Who Uses This
API Developers
validating JSON request and response payloads during integration testing, catching syntax errors like trailing commas and missing quotes before they cause runtime parsing failures in production
DevOps Engineers
checking JSON configuration files for CI/CD pipelines, container definitions, and infrastructure-as-code templates where a single syntax error can prevent deployments from running
Data Analysts
verifying JSON data exports before importing them into analytical tools or databases, ensuring that malformed JSON does not silently truncate or corrupt data during the import process