JSON Validator
Paste or upload JSON to instantly check whether it's valid — with the exact line and column of any error — plus an optional JSON Schema validation mode.
Need to reformat instead of just validate? Use the JSON Formatter, which validates and pretty-prints in one step.
How to validate JSON online
- Paste your JSON into the input pane, or drag a
.jsonfile onto it. - The validator checks it instantly against the JSON specification (RFC 8259).
- If it's invalid, the exact line and column of the problem is shown immediately.
- Optionally, toggle on schema validation and paste a JSON Schema to check your data's structure, not just its syntax.
Why use this JSON validator
Precise, not generic
Instead of a bare "invalid JSON" message, you get the exact line and column of the failure, so you're not scanning hundreds of lines by eye.
Schema-aware
Beyond syntax, you can optionally check that your JSON actually matches a required structure — types, required fields, enums, and numeric/string ranges.
Private by design
Validation runs entirely client-side. Your JSON, including sensitive payloads, is never uploaded anywhere.
No sign-up, no limits
Free JSON validator online, no account, no artificial size cap.
Why JSON validation matters
A JSON validator answers one specific question: does this text conform to the JSON specification? That's a narrower question than "does this data make sense," but it's the one that determines whether JSON.parse() in any programming language will succeed or throw. A single missing comma, an unescaped quote inside a string, or a trailing comma after the last item in an array is enough to make an entire document invalid — and those are exactly the mistakes that are hardest to spot by eye in a long file.
This tool checks syntax the moment you stop typing, and reports failures with the same precision a strict parser would give a developer: the line number and column where parsing broke down. That's usually enough to fix the problem in seconds instead of scanning the whole document.
Syntax validity is necessary but not always sufficient. If you're consuming an API response or producing a config file that other systems depend on, you often care about more than "is this valid JSON" — you care whether it has the right fields, the right types, and the right structure. That's what the optional JSON Schema mode adds: paste a schema alongside your JSON and the validator checks required properties, value types, allowed enum values, and basic numeric/string constraints, on top of the baseline syntax check.
Whether you call this a JSON checker, a JSON linter, or a JSON validator online, the underlying job is the same, and it's a step worth automating rather than eyeballing — especially before shipping a config file, an API payload, or a data export that another system will parse without forgiving you for a stray comma.
Frequently asked questions
What does a JSON validator actually check?
It checks whether your text conforms to the JSON specification (RFC 8259) — correct use of braces, brackets, quotes, commas, and value types. This is different from a JSON linter's style rules; validation is strictly about whether the JSON is well-formed.
What is JSON Schema validation, and do I need it?
JSON Schema validation checks not just that your JSON is syntactically valid, but that it matches a specific structure you define — required fields, data types, allowed values, and more. It's optional here; toggle it on only if you have a schema to validate against.
Why does the validator show an error even though my JSON looks fine?
The most common invisible causes are trailing commas, single quotes, unquoted keys, or a stray comment — none of which are valid in strict JSON even though they're common in JavaScript. The validator points to the exact line and column.
Is this JSON linter the same as a validator?
In casual usage, JSON validator, JSON checker, and JSON lint all refer to the same core task: confirming your JSON is syntactically correct. This tool covers that, plus the optional schema-matching step above.