JSON to YAML Schema Generator
Generate JSON Schema from sample JSON data, with output in JSON or YAML format.
About This Tool
The JSON to YAML Schema Generator is a free, browser-based utility that automatically creates a JSON Schema definition from any sample JSON data and outputs it in either standard JSON or YAML format. This is especially useful when you need schema definitions for CI/CD configuration files, Kubernetes manifests, Helm charts, GitHub Actions workflows, and other YAML-centric ecosystems where validation is critical.
JSON Schema is the industry-standard vocabulary for describing the structure of JSON documents. It powers API contract validation, configuration file linting, form generation, and code generation tools. While JSON Schema is defined as a JSON document, many DevOps and platform engineering teams prefer YAML for readability. This tool bridges that gap by letting you generate schemas directly in YAML format without any manual conversion.
The generator performs recursive type inference across your entire
JSON structure. Primitive values are mapped to their corresponding
JSON Schema types — string,
number, integer,
boolean, and null. Nested objects
produce nested schema definitions with their own
properties blocks. Arrays are analyzed to determine a
consistent element type; if the array contains mixed types, a
oneOf composition is generated. Each property
automatically receives a human-readable title derived
from its key name.
All processing happens entirely in your browser using native JavaScript APIs. Your data never leaves your machine — there are no server round-trips, no logging, and no third-party analytics on your input. This makes the tool safe for sensitive payloads such as internal API responses, secrets-containing configuration files, and production data samples. You can choose between Draft-07 and Draft 2020-12, toggle required fields, embed example values from your input data, and add description placeholders for documentation.
How to Use
- Paste or type your sample JSON into the Sample JSON panel on the left.
- The generated schema appears automatically in the right panel as you type.
- Select the Output Format to switch between JSON Schema in YAML or JSON format.
- Choose the Draft Version (Draft-07 or Draft 2020-12) to set the
$schemaidentifier. - Toggle All required to include or exclude
requiredarrays for each object level. - Enable Include examples to embed sample values from your input data directly into the schema, or enable Include descriptions to add empty placeholder fields for documentation.
- Click Copy or press Ctrl+Shift+C to copy the generated schema to your clipboard. Use Ctrl+Enter to generate from an empty state using the built-in sample.
Popular JSON to YAML Schema Examples
FAQ
What is JSON Schema and why would I want it in YAML format?
JSON Schema is a declarative language for describing the structure of JSON data. It is used for API validation, configuration linting, and form generation. Many DevOps tools (Kubernetes, Helm, GitHub Actions) use YAML natively, so having schemas in YAML format makes them easier to read, review, and maintain alongside your YAML configuration files.
Is the YAML output valid JSON Schema?
Yes. The output follows the JSON Schema specification exactly. YAML is a superset of JSON, so any valid JSON Schema expressed in YAML is semantically identical to its JSON counterpart. Most schema validation tools accept YAML input directly, and you can always convert back to JSON if needed.
How does the tool handle nested objects?
Each nested object in your JSON is recursively analyzed and produces a nested schema with its own type, properties, and optional required fields. The nesting depth is unlimited, so deeply nested structures like multi-level configuration files are fully supported.
What happens with arrays of mixed types?
If all elements in an array share the same type, a simple items schema is generated. If the array contains elements of different types (e.g., strings and numbers), the tool produces a oneOf composition listing each distinct type. Empty arrays produce an open items schema that you can refine manually.
Is my data safe?
Yes. All schema generation runs entirely in your browser using JavaScript's built-in JSON.parse and custom inference logic. No data is sent to any server. You can verify this by checking the Network tab in your browser's developer tools while using the tool.
What is the difference between Draft-07 and Draft 2020-12?
Draft-07 is a widely supported and stable version of JSON Schema used by many tools and libraries. Draft 2020-12 is a newer version that introduces improved vocabulary for dynamic references, prefixItems for tuple validation, and cleaner semantics for conditional schemas. For most use cases the generated schema is compatible with both versions; the main difference is the $schema URL that identifies which specification the schema conforms to.
Can I use the generated schema with Kubernetes or Helm?
Absolutely. The YAML output can be used directly as a values.schema.json (in YAML form) for Helm chart validation, or as a schema definition for custom resource definitions (CRDs) in Kubernetes. You can also use it with tools like kubeval, kubeconform, or VS Code YAML extensions to validate your manifests against the schema.
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