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JSON Validator - Check JSON Syntax Online

Validate JSON files in your browser and get the exact parser error position when syntax breaks. No upload, no account, instant verdict.

Quick start

Built for check if your json file is valid and find any errors.

Everything runs in your browser, so you can test the workflow with sample data when available before using production files.

Output: A new file or report produced locally in your browser.

  1. 1Choose a supported file or use sample data when available.
  2. 2Set the options shown for this workflow.
  3. 3Process the file locally, inspect the result, and download a new copy.
Preparing your private workspace…

How to Validate JSON

  1. 1Upload your .json file.
  2. 2The tool runs a full strict JSON parse.
  3. 3Valid files return a clean pass report.
  4. 4Broken files show the exact error message so you can fix the line.

Why Use This Tool?

  • ✓Precise Errors - Parser messages pinpoint what broke
  • ✓Strict Spec - Catches trailing commas and unquoted keys
  • ✓Instant Feedback - Results appear as fast as the parse runs
  • ✓Confidential - Validate sensitive configs locally

Frequently Asked Questions

Does it validate against a schema?

It checks syntax only. Generate a schema for your CSV-derived data with the CSV Schema tool, then validate elsewhere against it.

Why does valid-looking JSON fail?

Common culprits are trailing commas, single quotes, comments, or hidden BOM characters copied from word processors.

Is my API key exposed?

Never. The file is read by your browser only — nothing is transmitted, logged, or cached on any server.