JSON Validator
Validate JSON instantly and find syntax errors before they cause problems.
Paste your JSON, check its syntax, locate errors, inspect its structure, and get helpful validation feedback directly in your browser.
Valid JSON
Your JSON is syntactically valid.
Syntax Error Diagnostics
Approximate location: Line 1, Col 1Check commas, quotes, brackets, and braces.
JSON Statistics & Size Analysis
Calculated from parsed ASTSimple 3-Step Process
How to Validate JSON
Diagnose API payload errors, inspect structures, and format documents in seconds.
Paste Your JSON
Paste raw JSON from APIs, config files, or logs into the editor, or pick from our realistic presets.
Validate the Syntax
Click "Validate JSON" or toggle typing validation. The parser immediately flags syntax errors, line locations, and recommendations.
Fix, Format, or Export
Apply fix recommendations, switch to Tree View or Minified views, copy the clean JSON, or download the validated file.
What Is JSON?
JSON (JavaScript Object Notation) is a lightweight, universal, text-based data format designed for representing structured data. It is easy for humans to read and write and simple for machines to parse and generate.
{
"name": "ToolFenix",
"active": true
}JSON Syntax Rules
Strict Double Quotes
Both property keys and string values must be enclosed in double quotes ("). Single quotes (') are strictly invalid.
No Trailing Commas
Never leave a trailing comma after the last key-value pair in an object or after the last element in an array.
No Comments
Standard JSON does not support comments (neither // nor /* */). All commentary must be stored inside valid data attributes.
Supported Primitive Types
JSON values must be one of: Object {}, Array [], String, Number, Boolean (true/false), or null.
JSON Syntax vs. JSON Schema Validation
Syntax Validation: Confirms that character tokens, brackets, quotation marks, and commas comply with the universal JSON specification.
Schema Validation: Evaluates whether valid JSON adheres to a predefined business structure (e.g., verifying that an "email" field exists and contains a valid email format). This tool focuses on syntax validation.
Engineered For Reliability
Why Use ToolFenix JSON Validator?
Instant Error Detection
Pinpoints parser errors, estimates problematic line numbers, and highlights exact line positions.
100% Client-Side Privacy
Zero network transit. Your private payloads, API tokens, and credentials never touch a remote server.
Interactive Tree View
Traverse complex data hierarchies, inspect JSONPath references, and expand or collapse branches.
Comprehensive Statistics
Detailed AST metrics revealing counts for keys, objects, arrays, primitives, and maximum nesting depth.
Perfect For
API Developers
Frontend Engineers
QA Testers
Data Analysts
Got Questions?
Frequently Asked Questions
JSON.parse() engine alongside custom lexical heuristic functions to pinpoint error character locations and line numbers without running dangerous eval() calls.