JSON Swiss

JSON Swiss

Swift Struct to JSON Schema Generator

Need JSON to Swift?
JSON → Swift Structs

Swift code Input

Loading editor…

JSON Schema Output

Settings

Select which struct/class should be treated as the JSON Schema root.

Parsing runs entirely in your browser. Your source never leaves the page.

Paste your Swift models to produce JSON Schema instantly.

Supports Codable structs, optional types, arrays, dictionaries, and nested models.

How to convert Swift structs to JSON Schema – step-by-step guide

This online Swift struct to JSON Schema converter helps you generate JSON Schema from real models (DTOs, structs, and classes) so you can validate payloads, share contracts, and generate mock JSON.

  1. Step 1 – Paste your Swift source

    • Paste the models you want to document into the left editor.
    • Include referenced types in the same snippet so the schema can generate definitions.
    • Use the Sample button to load an example and see the expected input format.

  2. Step 2 – Select the Root type (if needed)

    • If multiple definitions are detected, choose the root that matches your API payload.
    • The output schema is built around the selected root and may include additional definitions for referenced types.

  3. Step 3 – Review the JSON Schema output

    • Check types, required vs. optional fields, and nested object/array structures.
    • Look for definitions and $ref when your models reference other models.
    • Copy or download the schema for validation, documentation, or schema-first development.

  4. Step 4 – Validate or generate mock JSON

    • Click Generate Mock Data to open the mock generator with your schema preloaded.
    • Validate real payloads against your schema to catch breaking changes early.
    • If you rely on advanced schema composition (for example anyOf/oneOf/allOf), verify the result with a full validator like Ajv.

Schema keyword support note

Generated schemas can include $ref and may be edited to include anyOf, oneOf, or allOf. For complex schemas, use a full JSON Schema validator and dereference before mock generation if needed.

Related JSON Schema & code generation tools

Use these tools to validate schemas, generate mock payloads, format JSON examples, and keep code and contracts in sync.

JSON Schema Mock Data Generator

Generate example JSON from your schema for testing, fixtures, and documentation.

JSON Schema Validator

Validate JSON against common schema keywords and find mismatches quickly.

JSON to Swift Structs

Generate Swift types and models from JSON samples.

JSON to JSON Schema Generator

Build schema from representative JSON samples to complement model-first schemas.

JSON Schema Library

Explore schema examples and patterns for objects, arrays, enums, and constraints.

JSON Formatter

Clean up JSON examples before validating against schema or sharing docs.

Frequently Asked Questions

Which Swift types are supported?

The tool parses structs and classes with stored properties. It handles optional types (String?), arrays, dictionaries, default values, Codable annotations like @CodingKey (ignored but safe), and nested types. Paste models directly from your Swift or SwiftUI project.

How are Swift types mapped to JSON Schema?

String/Int/Double/Bool map to schema primitives, arrays like [Address] become schema arrays, dictionaries map to objects, and optional types become optional fields. Unknown custom types fall back to strings unless another struct/class with that name exists in the input.

Can I include multiple structs?

Yes. Paste several related structs and choose the root type from the settings dropdown. Everything runs locally in your browser, so no source code is uploaded.

How do I create mock JSON data?

After generating the schema, click "Generate Mock Data" to open the Mock Generator with your schema preloaded. Configure locales, array counts, and optional fields to create sample payloads instantly.

Convert Swift Structs to JSON Schema Online | JSONSwiss