JSON Validator — Check Your JSON for Errors

Quick answer

Paste any JSON and this validator checks it instantly with the browser's own JSON.parse — the same strict parser your application will use. Valid input turns green; invalid input shows the error message plus the line and column, so you fix the real problem instead of guessing.

Last updated: October 16, 2026

A validator's job is to say no early. This one runs on every keystroke, so the moment your document breaks — a missing quote, a trailing comma, a stray bracket — you see exactly where it happened. No button to press, no account to create, and no data sent anywhere: the checking is done by JavaScript in your own browser.

Use the tool below

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Valid JSON — 381 B

{
  "project": "CodeLive Studio",
  "version": "1.4.2",
  "free": true,
  "signupRequired": false,
  "tags": [
    "html",
    "css",
    "javascript"
  ],
  "privacy": {
    "uploadBytes": 0,
    "storage": "browser-localStorage",
    "price": 0
  },
  "editors": [
    {
      "name": "HTML",
      "emmet": true
    },
    {
      "name": "CSS",
      "emmet": true
    },
    {
      "name": "JavaScript",
      "console": true
    }
  ]
}

30 lines · 443 B

JSON Validator runs entirely in your browser — nothing you paste or type is uploaded to any server, and no account is needed.

How do I validate JSON online?

1
Paste your JSON into the editor, or upload the file — validation starts immediately, no button needed.
2
Read the status bar: green means the document parses (and shows its size); red means the parser failed and reports why.
3
Follow the line and column in the error message to the exact spot — the most common fixes are removing a trailing comma or quoting a key.
4
Once valid, the formatted view on the right confirms the parsed structure — what you see is exactly what JSON.parse produced.

Why validate here instead of in your code?

The strictest referee: JSON.parse itself

Some online checkers are more forgiving than real parsers, which produces false confidence. This tool uses the browser's native JSON.parse — the exact behavior of every JavaScript runtime — so passing here means passing in production.

Errors with coordinates, not riddles

"Unexpected token } at position 412" becomes line and column, pointing at the character that broke the document. Most JSON errors are found and fixed in under a minute with that one detail.

Checks as you type

There is no validate button to remember. Edit, glance at the badge, keep going — the loop between mistake and diagnosis is a fraction of a second.

Safe for confidential payloads

Validation is pure client-side computation: no upload endpoint exists to receive your JSON. Webhook secrets, tokens and customer records can be checked without a second thought.

Free forever, no account

Every feature — file upload, downloads, live checking — is free with no signup. A validator is a two-second utility; paywalls and registration walls do not belong anywhere near it.

From diagnosis to fix in one page

Once the document is valid, the formatter output is already there — switch the style, copy the result or download it. You rarely need a second tool after this one.

Common JSON errors and how to fix them

The five messages people see most, what each one actually means, and the fix — a reference worth keeping open while you clean up a document.

Error message	What it means	How to fix
Unexpected token } in JSON	Usually a trailing comma before a closing } or ] — the most common JSON mistake by far	Delete the comma after the last element of the object or array
Unexpected token ' in JSON	Single quotes were used for strings or keys; JSON only allows double quotes	Replace every '...' with "..." (and escape inner double quotes as \")
Unexpected token n in JSON / bare word	A key was written without quotes (name: "Ada") or a value like True/None came from Python	Quote every key, and use JSON literals: true/false/null — not True/False/None
Unexpected end of JSON input	The document ends mid-structure — a bracket or brace was opened but never closed, or the paste was truncated	Check bracket balance at the end of the file; re-copy the whole payload if it was cut off
Unexpected token < in JSON	The input is HTML (often an error page) rather than JSON — typically a failed API request returning a web page	Inspect what the request actually returned; fix the endpoint or the request before validating again

Exact wording varies slightly between browsers, but the causes are the same everywhere. The validator's line and column tell you where to look; this table tells you what to do.

What does "valid JSON" actually guarantee?

Syntactic validity means the document parses: correct brackets, correct quotes, correct literals. It does not mean the data is semantically right — a schema that expects an array of numbers will still choke on an array of strings, and only a schema validator (JSON Schema and friends) can check that layer. Know which problem you are solving: for syntax, this page is the fastest check; for structure, validate against a schema in your codebase.

Why use the browser's parser instead of a gentler one? Because JSON.parse is what will run against this data in real life — in your frontend, your Node service, your serverless function. A validator that accepts what production rejects is worse than no validator at all. Strictness here is a feature, not an inconvenience.

Questions this tool answers

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Frequently asked questions

Is this JSON validator free to use?

Yes — completely free with no account and no limits. Validation runs in your browser via the native JSON.parse, so there is no per-check server cost, which is exactly why the tool can stay open and unlimited.

Does validating send my data to a server?

No. The checking happens entirely in your tab, and the page has no upload endpoint. Whatever you paste — including secrets — stays on your device, with only a local auto-save copy in your browser's storage.

Can the validator tell me where the error is?

Yes. When JSON.parse fails, the tool extracts the error position and converts it to a line and column, displayed right under the editor. Combined with the error table on this page, most mistakes take under a minute to fix.

Does it check JSON schema, not just syntax?

It validates syntax — the layer every downstream tool depends on. Schema-level rules (required fields, types, ranges) belong to JSON Schema tooling in your project; feeding this validator a syntactically clean document is the right first step before that.

Can I validate several documents at once?

One document at a time — JSON has no standard multi-document syntax (unlike NDJSON). If you have line-delimited JSON, split it into single lines and validate one row, or wrap the lines in an array first.

JSON Validator — Check Your JSON for Errors

How do I validate JSON online?

Why validate here instead of in your code?

The strictest referee: JSON.parse itself

Errors with coordinates, not riddles

Checks as you type

Safe for confidential payloads

Free forever, no account

From diagnosis to fix in one page

Common JSON errors and how to fix them

What does "valid JSON" actually guarantee?

Questions this tool answers

Frequently asked questions

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