JSON Validator Online

Check JSON syntax locally, find the exact error line and column, and preview valid JSON with clean formatting.

input.json · strict
output.json · 2-space
Paste JSON and click Validate to check syntax.

Related

Guides for Validate

All guides →
Guide

JSON Parse Errors: Read the Message, Jump to the Fix

A directory of JSON parser error messages and the article that explains each one — start with a strict validator, then drill into the specific syntax problem.

Guide

Fix Trailing Comma in JSON

A trailing comma after the last object property or array item is valid in some JavaScript contexts, but it is not valid JSON.

Guide

Fix Single Quotes in JSON

JSON strings and object keys must use double quotes. Single-quoted values are common in JavaScript snippets, Python-like output, and LLM responses.

Strict JSON syntax validation

This validator runs a strict parse against RFC 8259. It reports the exact line and column of the first syntax error, highlights the offending character in the editor, and shows a formatted preview when the input is valid. No data leaves your browser.

The same workflow goes by many names — jsonlint, json lint, json linter, json checker, check json online, validate json online, validation json online, validate online json, online json parser, json parser online, json verify / json verification, json validator online, or json object validator. They all describe the same operation: feed in a string, confirm it parses as JSON, and pinpoint the first failure when it does not — useful when you need to parse json object online or convert string to json safely before using it elsewhere. In Python the equivalent is json.loads (also written json loads, or python parse json); in JavaScript, JSON.parse (sometimes searched as jsonobject.parse) — both throw on the same syntax errors this tool reports.

Common validation errors

  • Single quotes — JSON requires double quotes around strings and keys
  • Trailing commas — the last item in an object or array must not be followed by a comma
  • Unquoted keys — every object key must be a double-quoted string
  • Comments — // line and /* block */ comments are not valid JSON
  • Python literals — True, False, None must be true, false, null

If your JSON fails validation, use the JSON Fix tool to auto-repair common mistakes before re-validating.

FAQ

What's the difference between validating and parsing JSON?

Parsing turns the JSON text into a usable value; validating just confirms it could be parsed. A successful JSON.parseis the validation — you discard the result when you only care about validity.