JSON Validator - Check JSON Syntax Free

Paste JSON and instantly know if it is valid. Clear error messages show exactly where the syntax problem is. Free, no account.

How to Use JSON Validator

Enter JSONPaste or type your JSON into the textarea above

ValidateClick the button to check if JSON is valid

ReviewSee results with details about the JSON structure

JSON Validator - Free Developer Utility

JSON Validator - instantly check whether any JSON string is syntactically valid. API responses, configuration files, database exports, and user-submitted data all need validation before processing. A single missing comma, an extra bracket, or an unquoted key can crash your application or silently corrupt data. Our json validator catches these errors immediately and reports the exact location and nature of the problem. The validator also reports the type (object or array), property count, and array length of valid JSON, giving you a quick structural overview before parsing. Use it during API development, debugging data pipelines, or verifying generated configuration files.

Keywords and Common Use Cases

Developers search for this tool using terms like: json validator, validate json, json syntax checker, check json, is json valid. Used by backend developers, frontend engineers, DevOps professionals, and students working on web projects.

Zero Data Retention Policy

Every input you enter is processed in memory and immediately discarded. We do not log inputs, store results, or send your data to any third party. Code, API tokens, passwords, and sensitive strings remain completely private.

Frequently Asked Questions

Valid JSON must have: all keys in double quotes, all string values in double quotes, no trailing commas, correct nesting of brackets and braces, and values that are strings, numbers, booleans, null, objects, or arrays.

Trailing commas after the last property or array item, single quotes instead of double quotes for strings or keys, missing quotes around keys entirely, unescaped special characters in strings, and mismatched brackets.

Our tool performs syntax validation - checking whether the JSON is structurally correct. JSON Schema validation is semantic - checking whether the values match expected types and constraints.

Yes. The validator handles any valid JSON size. Very large files (100MB+) may take a moment but there is no hard rejection limit.

JSONP wraps JSON in a function call and is an old workaround for cross-origin restrictions. JSONP is not valid JSON. Our validator correctly identifies JSONP as invalid JSON.