JSON Validator
Format & ValidateValidate, verify, and check JSON — every syntax error pinpointed by line and column.
Validate JSON and find the exact error
A JSON validator checks whether text is well-formed JSON and, when it is not, tells you precisely what went wrong and where. This validator follows RFC 8259 — the official JSON specification — so its verdict matches what the strict parsers in your production language will accept. If JSON.parse would throw, this tells you why first.
Instead of a cryptic parser dump, you get a plain-English explanation pinned to an exact line, column, and character offset: a missing comma, an unquoted key, a trailing comma, or an unescaped quote inside a string.
Validate first, then format
This page does one job: it tells you whether your JSON is valid and, if it isn't, exactly what is wrong and where. Your input is checked against the RFC 8259 specification as you type, and every error is flagged with its line and column, so you can fix the document before anything downstream tries to parse it.
Once it passes, open it in the JSON formatter and beautifier to indent, minify, or sort keys. Both tools share the same parser, so a document that validates here will format cleanly there, and an error reported here is the same error the formatter would stop on.
JSON verification — what it means and how it works
JSON verification means confirming that a piece of text is syntactically valid JSON. The terms JSON validation and JSON verification are interchangeable — both mean checking your text against the grammar defined in RFC 8259.
Common reasons JSON verification fails: trailing commas after the last key or array item, single quotes instead of double quotes, unquoted property keys (legal in JavaScript but not in JSON), inline comments (// or /* */), and Python-style True, False, or None literals. Paste your text above and the tool flags the first violation with its line, column, and a plain description of the problem.
Why “Unexpected token” errors happen
Most JSON validation failures come from a short list of mistakes. Knowing them makes the fix obvious:
- Trailing commas after the last item in an object or array.
- Single quotes — JSON requires double quotes around strings and keys.
- Unquoted keys, which are legal in JavaScript but not in JSON.
- Comments, which JSON does not allow at all.
- Unescaped control characters or quotes inside string values.
JSON checker online — check any JSON instantly
A JSON checker online reads your text and reports whether it conforms to the JSON specification. Use this checker to verify an API response before parsing it in code, to confirm a config file is valid before deploying, or to debug a payload that is failing a production parser.
Because the check runs entirely in your browser, it works safely on sensitive data — tokens, credentials, or customer records — without any upload to a server. Paste, check, fix, and move on.
Lint and check JSON syntax online
A JSON linter and a JSON validator do the same core job: confirm your text is valid JSON and surface the exact problem when it isn't. Paste a payload to check JSON syntax online before you ship it in an API request, a config file, or a database column — catching a bad escape or a stray comma here is far cheaper than debugging a 400 in production.
Every error comes with a line, a column, and a plain-English reason, so “invalid JSON” turns into an actionable fix rather than a guessing game.
What is valid JSON?
Valid JSON is text that conforms to the grammar defined in RFC 8259 — the official JSON specification. To be valid, a JSON document must use double quotes around all strings and keys (not single quotes), omit trailing commas after the last item in objects and arrays, contain no JavaScript-style comments, and use only the literals true, false, and null (not True, False, None, undefined, NaN, or Infinity).
Paste your text above to check whether it is valid JSON online — the validator parses it against RFC 8259 and returns an instant verdict. If the JSON is invalid, you get the exact line, column, and a plain-English description of the problem, so the fix is obvious rather than a guessing game.
Everything in the JSON Validator
Free JSON validator — paste JSON to validate syntax and find errors with line and column numbers. Plain-English error messages. Free and private.
Precise errors
Exact line, column, and offset for every problem.
Readable messages
Plain-English explanations, not cryptic parser dumps.
RFC 8259 compliant
Strict checking against the JSON standard.
Instant feedback
Validity updates live as you edit.
Frequently asked questions
Paste your JSON and the validator highlights the first error with its line and column, plus a description such as a missing comma, unquoted key, or trailing comma.
Validation follows RFC 8259, the official JSON specification, so results match what strict parsers in production languages will accept.
Yes. Linting and validating JSON are the same job — the tool checks your text against the JSON standard and reports the first error with its line, column, and a plain-English reason, so you can lint and fix JSON syntax in one place.
A JSON formatter and validator is a tool that does two jobs together: it checks your JSON against the specification — catching syntax errors like missing commas, unquoted keys, or trailing commas — and it can also format (beautify) the result with clean indentation. Using a formatter and validator together saves you from copying output between two separate tools.
Paste your JSON into the editor above — verification runs instantly as you type. If the JSON is valid you see a green confirmation; if not, the exact line and column of the problem is highlighted with a plain-English reason. JSON verification and JSON validation are the same thing: both confirm your text conforms to RFC 8259.
A JSON checker reads your JSON text and checks it against the JSON specification. It reports whether the JSON is valid and, if not, pinpoints the exact location and reason for the first error — a missing bracket, an extra comma, an unquoted key, or an illegal character. This tool is a JSON checker, linter, and validator in one.
Yes. Click 'Load from URL', paste any public URL that returns JSON — an API endpoint, a raw GitHub file, or a CDN asset — and the content loads instantly in your browser. The request goes directly from your device; nothing passes through our servers.
No. Every operation runs entirely in your browser using client-side JavaScript. Your JSON is never uploaded, logged, or stored on any server — it never leaves your device.
Yes, completely free with no sign-up required. There are no usage limits, no watermarks, and no premium gate on any feature.
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