JSON Validator for API Responses

About This Tool

Working with REST APIs, GraphQL endpoints, and webhooks means constantly processing JSON response data. Raw API responses are typically minified — stripped of all whitespace and line breaks to minimize payload size — making them virtually impossible to read without formatting. This tool transforms those compact responses into well-structured, readable output that reveals the data hierarchy and makes it easy to locate specific values. Paste a response from Postman, cURL, browser DevTools Network tab, or any API client, and instantly see the formatted result. The tool validates the response structure during processing, catching malformed responses that might cause subtle bugs in your application. For developers debugging production issues, this immediate visibility into API data structures is invaluable.

What is JSON Validator?

A JSON validator checks whether a string of text conforms to the JSON specification (RFC 8259). It identifies syntax errors such as missing commas, unmatched brackets, invalid escape sequences, trailing commas, and single quotes (which are not valid in JSON). Beyond syntax checking, this validator also reports structural information: the root data type (object, array, string, number, boolean, null), the number of top-level keys, array lengths, and the overall data size in bytes. Validation is essential before processing JSON data in applications, submitting API payloads, or storing configuration files to prevent runtime errors and data corruption.

How to Use This Tool

1. Paste your JSON into the input field.
2. Click Validate JSON.
3. See whether the JSON is valid or invalid.
4. Review the type, size, and key information.

Common Use Cases

• Formatting raw API response bodies for debugging
• Processing webhook payloads for analysis
• Cleaning up GraphQL query responses
• Inspecting third-party API data structures

Examples

{"valid": true, "items": [1, 2, 3]}

{"invalid": true,}  // trailing comma

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