JSON Validator

Key takeaways

• Instant parse check in the browser
• Reports node counts and size for valid input
• Shows line/column for many parse failures
• Private - nothing is sent to a server

What does JSON validation mean?

Validation confirms that a string parses as JSON according to the language grammar (objects, arrays, strings, numbers, booleans, null).

It does not prove business-rule correctness. Duplicate keys follow JSON.parse behavior (last key wins). Use this tool before shipping payloads or debugging API clients.

Features

• Instant validation

  JSON is checked automatically as you paste or type.

• Structure report

  See type, node count, character count, and UTF-8 byte size.

• Precise errors

  Invalid documents highlight line/column whenever the parser provides them.

• Exportable report

  Copy or download a plain-text validation report for tickets and reviews.

How it works

1. 1

   Paste or upload JSON

   Drop a file or paste JSON into the input panel.

2. 2

   Validate automatically

   Valid documents show a report with type and size. Invalid ones highlight the error location.

3. 3

   Copy or download the report

   Export the validation summary for debugging or reviews.

Example walkthroughs

• Valid payload

  A valid object reports type object plus node and size metrics.

  {"ok":true,"count":2,"items":["a","b"]}

• Invalid trailing comma

  Trailing commas are invalid in JSON and surface as a parse error.

  {"ok":true,}

Use cases

• QA API contracts

  Verify fixtures and mocked responses before running integration tests.

• Support triage

  Confirm whether a customer-provided payload is syntactically valid.

• CI sample checks

  Quickly lint sample JSON used in docs or seed data.

Code snippets

• Validate with try/catch

  js

  Mirrors this tool’s parse check - success vs parser message.

  try {
    JSON.parse(raw);
    console.log("valid");
  } catch (error) {
    console.error(error.message);
  }

Common errors

• Unexpected end of JSON input

  Cause: The payload was truncated or still streaming when copied.

  Fix: Paste the complete document, including the final } or ].

• Valid JS object fails validation

  Cause: Unquoted keys, trailing commas, or undefined are not valid JSON.

  Fix: Convert to strict JSON (double quotes, no trailing commas) first.

About JSON Validator

JSON Validator checks whether a document is syntactically valid JSON and reports useful structure stats when it is - root type, node counts, character length, and approximate UTF-8 size. Use it before shipping API clients, CI fixtures, or config that must parse everywhere.

When validation fails, you get a clear parser message with line and column guidance so you can fix trailing commas, missing braces, unquoted keys, and other common issues copied from JavaScript object literals. Syntax validity is not the same as schema or business-rule correctness.

Processing stays in your browser. Paste suspicious payloads, redacted samples, or large exports without uploading them to a third-party lint service. Export a plain-text report when you need evidence in a ticket or pull request.

Best practice: validate first, then open JSON Formatter or Viewer. If you only need to escape a string value, use JSON Escape instead of treating the whole document as invalid. For semantic changes between two versions, prefer JSON Compare after both sides validate.

Frequently asked questions

Explore more

• All developer tools

  Browse formatters, converters, encoders, and more.

• JSON tools category

  Format, validate, view, compare, diff, and escape JSON.

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