CODDY Tool

JSON Validator

Check whether JSON is valid and get the exact location of any error.

Validate JSON and find out precisely where it breaks. Errors come with a line and column, a highlighted excerpt, and an explanation of what the parser expected.

Everything you enter stays in this browser tab. Nothing is sent to our servers, logged or stored.

This is one of the thingsJSON Tooldoes — open it for everything else it supports.

Loading tool…

What JSON Tool supports

Clean up

  • Format & beautify
  • Minify
  • Validate
  • Tree view
  • Sort keys

Convert

  • JSON → CSV
  • CSV → JSON
  • JSON → YAML
  • YAML → JSON
  • JSON → XML
  • XML → JSON

About JSON Validator

A single misplaced character invalidates an entire JSON document, and the message a parser produces is often unhelpfully terse. "Unexpected token" tells you something is wrong without telling you where or why.

This locates the problem: the line, the column, an excerpt with the offending character marked, and a plain explanation. When the document is valid you get a structural summary instead — the top-level type, how many keys or elements it holds, and its maximum nesting depth — which is a fast check that a response is the shape you expected.

How to validate JSON

  1. Paste your JSON

    Validation runs as you type.

  2. Read the result

    Valid documents get a structural summary; invalid ones get the error location.

  3. Fix and re-check

    Correct the highlighted problem and the status updates immediately.

Frequently asked questions

Is my data uploaded for validation?

No. Validation uses your browser's own JSON parser, so payloads containing credentials or customer data never leave your machine.

Are trailing commas allowed in JSON?

No, and this is the most common JSON error by a wide margin. JavaScript permits a trailing comma in array and object literals; the JSON specification does not.

Can I use comments in JSON?

No. The specification has no comment syntax. Some parsers accept JSON5 or JSONC extensions that add them, but a standard parser will reject them. Add a description field to the data instead.

Does this validate against a schema?

No, it checks syntax only — whether the text is well-formed JSON. Verifying that a document matches an expected shape needs a JSON Schema validator, which is a separate step.

Related tools

All Developer Tools

JSON Formatter

Developer Tools

Beautify minified JSON with proper indentation and a tree view.

JSON Tool

Developer Tools

Format, validate, minify and convert JSON to CSV, YAML and XML.

Encoding Tool

Developer Tools

Encode and decode Base64, URL percent-encoding and HTML entities.

Regex Tester

Developer Tools

Test regular expressions with live match highlighting and capture groups.

Hash Generator

Security Tools

Generate MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes of text or files.

JSON Validator is free to use with no account, no watermark and no usage limits. Last updated 14 August 2026.