JSON Validator

JSON Validator — Lint & Validate JSON Online

Free online · Instant results · No signup

Free online. Instant results. Free JSON validator and JSON lint tool. Check if JSON is valid, catch syntax errors, and fix API payloads in your browser—no signup.

Wondering if a payload is valid JSON before you ship it to an API? This JSON validator checks syntax in your browser and tells you clearly when something is wrong—perfect for linting responses, config files, and webhook bodies.

About JSON Validator

A single trailing comma can break a deploy. Teams paste JSON into Slack or tickets and only discover syntax errors when the parser fails in CI. This validator gives you an immediate valid/invalid result so you can fix the issue before the next commit.

Paste the text, click Check, and read the result panel. Valid JSON reports the top-level type (object or array). Invalid JSON shows the parser message so you can jump to the problem—often an unexpected token, missing brace, or bad escape.

Use it beside our JSON Formatter when you want pretty output after validation, or alone when you only need a quick lint. No install and no account.

How to Use JSON Validator

  1. Paste the JSON you want to validate.
  2. Click Check to run the linter.
  3. Read the result: Valid JSON, or an error description to fix.
  4. Optionally open JSON Formatter next to pretty-print once it passes.

If validation fails on data that “looks fine,” search for smart quotes from Word/Docs—JSON requires straight double quotes.

Common Use Cases

Gatekeep CI fixture files

Validate seed JSON before pushing so pipelines fail less often on syntax.

Verify webhook samples

Confirm partner documentation examples are real JSON before writing handlers.

Check CMS export blobs

Lint exported content JSON from headless CMS tools before import.

Teach strict JSON rules

Show students how trailing commas and single quotes fail validation.

Why Use Fake Data Hub?

Validate, format, minify, and convert JSON on one free site—Fake Data Hub keeps the whole JSON toolkit in your browser.

Frequently Asked Questions

What does a JSON validator do?

It checks whether text is syntactically valid JSON. You get a pass result or an error message describing what the parser could not read.

Is this a JSON lint tool?

Yes. JSON lint and JSON validate are commonly used the same way for syntax checking. This page focuses on clear pass/fail feedback.

How do I check if JSON is valid online?

Paste it into the input box and click Check. You will see Valid JSON or an error without creating an account.

Does it validate against a JSON Schema?

This tool validates syntax (parseability), not JSON Schema types or required fields. Use a schema validator if you need structural contracts.

Why is my JSON invalid?

Typical issues: trailing commas, single quotes, unquoted keys, comments, or truncated strings. The error message usually points near the problem.

Can I validate minified JSON?

Yes. Compact one-line JSON validates the same as pretty JSON—whitespace does not matter for validity.

Is JSON validator free on Fake Data Hub?

Yes. Unlimited checks in the browser with no signup.

Should I validate before formatting?

Either order works. Validator is faster when you only need pass/fail; formatter needs valid JSON to pretty-print.

Does empty input count as valid?

Empty text is not valid JSON. A valid empty structure would be {} or [].

Can it validate JSON arrays?

Yes. Top-level arrays like [1,2,3] are valid JSON and will pass.

What about NaN or Infinity?

Those are not valid in standard JSON. Use null or strings if you need placeholders.

Will it fix my JSON automatically?

No. It reports problems so you can fix them. After it is valid, use JSON Formatter to pretty-print.

Is my payload uploaded?

Validation runs locally in the browser for normal use.

Can I validate GraphQL responses?

If the body is JSON, yes. GraphQL query language itself is not JSON and will fail—paste the JSON response, not the query.

Difference between validator and parser tools?

Validator answers “is it valid?” Parser tools also summarize structure and paths after a successful parse.