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JSON validator

Paste JSON and instantly check whether it's valid. If there's a syntax error, you'll get the exact line and column so you can fix it fast. Runs entirely in your browser — nothing is sent to a server.

What is JSON validation?

JSON validation checks whether a string conforms to the JSON grammar defined in RFC 8259. A valid JSON document must have correctly matched braces and brackets, double-quoted string keys, properly escaped special characters, and values that are strings, numbers, booleans, null, arrays, or objects — nothing else.

Invalid JSON breaks API calls, config files, data pipelines, and import scripts. A quick validation pass catches the problem before it reaches production.

Common JSON syntax errors

  • Trailing commas after the last item in an array or object
  • Single quotes instead of double quotes around keys or strings
  • Unquoted property keys
  • Missing or mismatched brackets and braces
  • Comments (JSON does not allow // or /* */)

JSON validation vs. schema validation

Syntax validation answers "is this valid JSON?" — it checks grammar only. Schema validation answers "does this JSON match a specific structure?" using a schema definition (like JSON Schema) that describes required fields, types, and constraints. This tool does syntax validation. If you need structural validation, try the JSON schema validator.

From validated JSON to instant insights

If you're working with JSON data for analytics or reporting, Basedash can skip the manual parsing entirely. Describe the chart or metric you want in plain English, and Basedash writes the query, runs it against your actual data, and renders the visualization — all in seconds. It connects to PostgreSQL, MySQL, BigQuery, Snowflake, and 750+ other data sources.

FAQ

What does this validator check?

It validates against the RFC 8259 JSON standard. It checks structure, syntax, string escaping, number format, and nesting.

Is my JSON stored or sent to a server?

No. Validation runs entirely in your browser using JavaScript. Your JSON is never transmitted, logged, or stored anywhere.

Can it fix invalid JSON?

No automatic fixing, but error messages include the exact position and description so you can fix issues quickly. Use the JSON formatter for beautifying valid JSON.

What's the difference between JSON validation and JSON schema validation?

This tool checks syntax — is it valid JSON? Schema validation checks structure — does it match a specific shape? This tool does syntax validation only.

Does it support JSON5 or JSONC?

No. This validates strict JSON per RFC 8259. JSON5 features like comments, trailing commas, and unquoted keys will be flagged as errors.

Can I validate large JSON files?

Yes. The browser's native JSON parser is fast and handles files up to several megabytes without issues.

Related tools

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