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DevToolKit

JSON Validator & Schema Checker

Industrial-grade JSON syntax and schema validator with line-number error pointing, auto-repair, and schema inference.

Strictly Compliant

Your JSON data follows RFC 8259 and matches the provided schema.

Validator Options

Verify against rules
Suggest syntax fixes

Line-level mapping uses json-source-map to pinpoint exact structural violations.

JSON DATA
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How to Use

Debugging and validating JSON is fast and precise with our diagnostic editor:

  1. Paste JSON: Enter your data into the JSON DATA input box.
  2. Identify Errors: If violations are found, look at the Diagnostic HUD in the sidebar for exact line numbers and error descriptions.
  3. Auto-Fix: Use the Auto-Fix Syntax button if available to instantly repair common syntax errors.
  4. Validate Schema: Toggle Schema Validation and paste your JSON Schema to verify complex data rules and types.
  5. Infer Schema: Don't have a schema? Click Infer Schema from Data to generate one automatically based on your current input.

About This Tool

Deep Structural Inspection

Most validators only tell you that a parse failed. Our JSON Validator goes deeper, using structural source-mapping to link schema violations back to the specific characters in your text. This makes it an essential tool for developers building high-reliability APIs or complex cloud configurations.

Why Use This Tool

Why use our tool?

Privacy-first diagnostics. While many online linting tools log your data or schema for analysis, DevToolkit performs all validation 100% client-side. Your sensitive API payloads, proprietary schemas, and internal documentation never leave your browser, ensuring complete security and compliance.

FAQ

Which JSON Schema drafts are supported?
Our validator uses the high-performance Ajv engine, supporting modern JSON Schema drafts including Draft 7, 2019-09, and 2020-12.
What is Schema Inference?
If you don't have a schema, our tool can 'Infer' one based on your data. This automatically generates a draft JSON Schema that you can then use to validate other documents.
Can this tool fix invalid JSON?
Yes. If syntax errors are detected (like trailing commas or missing quotes), an 'Auto-Fix Syntax' button will appear to instantly repair common RFC violations.
Is my data secure?
Absolutely. Validation happens 100% client-side in your browser. Neither your data nor your schema is ever uploaded to a server.