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YAML to JSON Schema Converter - Online OpenAPI Infer Structure

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YAML to JSON Schema

Paste your YAML data and instantly infer its JSON Schema structure — ideal for OpenAPI specs, config validation & API documentation.

YAML Input
0 chars
Inferred JSON Schema
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{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "properties": {}
}
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Frequently Asked Questions

This tool takes your YAML data and automatically infers a JSON Schema from its structure. It analyzes the types of each field — strings, numbers, booleans, arrays, nested objects — and generates a valid JSON Schema document. This is particularly useful for creating validation schemas for APIs, configuration files, and OpenAPI specifications without writing the schema manually.

The inference engine parses your YAML into a JavaScript object, then recursively walks through every key and value. For each field, it detects the primitive type (string, number, integer, boolean, null), nested object structures, and array item types. When arrays contain mixed types, the tool generates a oneOf schema. Optional features include automatic required field detection, examples inclusion, and format detection for dates and emails.

Absolutely. OpenAPI 3.x specifications use a subset of JSON Schema to define request bodies, responses, and parameters. You can paste any OpenAPI YAML fragment — such as a component schema, a request body definition, or an entire API spec — and this tool will extract and infer the corresponding JSON Schema structure. This is especially helpful when you need standalone JSON Schemas for validation libraries or documentation generators.

The tool supports all standard YAML data types: strings, integers, floating-point numbers, booleans (true/false), null values, arrays/lists, and nested objects/mappings. It also intelligently detects common formats like ISO 8601 dates (format: date or format: date-time) and email addresses (format: email), adding appropriate format annotations to the generated schema.

Nested objects are recursively traversed, creating nested properties blocks with their own type definitions. Arrays are analyzed to determine the type of their items — if all items share the same type, a single items schema is generated. If items have different types, the tool creates a oneOf array to accurately represent the possible item types. Empty arrays generate an empty items: {} schema.

The tool supports both JSON Schema Draft-07 (http://json-schema.org/draft-07/schema#) and Draft 2020-12 (https://json-schema.org/draft/2020-12/schema). You can switch between them using the Draft selector. Draft-07 is the most widely compatible version across tools and libraries, while Draft 2020-12 introduces newer features like $dynamicRef and unevaluatedProperties.

Common YAML parsing issues include: inconsistent indentation (YAML requires spaces, not tabs, and consistent indentation levels), unquoted special characters (colons, hashes, exclamation marks in string values should be quoted), and incorrect list formatting (use hyphens with proper indentation). The tool will display a detailed error message pointing to the problematic line when parsing fails.

Yes — the generated JSON Schema is fully standard-compliant and can be used with any JSON Schema validator, such as ajv (JavaScript), jsonschema (Python), json-schema-validator (Java), or online validators. Simply copy the output and use it in your validation pipeline. The schema accurately reflects the structure, types, and constraints inferred from your YAML data.
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