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Validate JSON

Check JSON syntax and review a formatted preview in your browser.

Browser-only processing: validation happens locally and your JSON is not uploaded.

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About JSON Validator

JSON Validator checks whether your JSON can be parsed correctly and helps you spot syntax issues faster. It is useful for APIs, config files, test payloads, and debugging. When the JSON is valid, you also get a formatted preview without sending data anywhere.

How to Validate JSON Online
  1. 1
    Paste your JSON

    Copy your JSON into the input editor.

  2. 2
    Run validation

    Check the JSON syntax in your browser and inspect any reported line or column details.

  3. 3
    Use the preview or fix the error

    If the JSON is valid, copy or download the formatted preview. If not, fix the reported syntax issue and validate again.

Frequently Asked Questions

What does JSON validation check?

It checks whether the JSON syntax is valid and can be parsed correctly by the browser.

Can this tool show line and column errors?

Yes. When the browser exposes the parsing location, the validator shows the related line and column details.

Does the validator also format valid JSON?

Yes. When the JSON is valid, the tool shows a formatted preview that you can copy or download.

Is validation done in the browser?

Yes. All validation is performed locally in your browser for privacy-first handling.

Why Choose Let Compress?
  • No file upload required - 100% client-side processing
  • Free to use with no registration needed
  • Batch compress multiple files at once
  • Optimised compression algorithms for best results
  • Works on all modern browsers and devices
  • No file size limits or compression quotas

Learn More About File Compression

Explore these authoritative resources to deepen your understanding of file compression and optimisation.

MDN Web Docs: Image Optimisation

Comprehensive guide on image optimisation for web performance by Mozilla.

Google Web Fundamentals: Image Optimisation

Best practices for image optimisation from Google's web performance team.

W3C WebP Specification

Official W3C specification for the WebP image format.