JSON to Kotlin Data Class Generator
Generate nested Kotlin model definitions from a JSON example. Review the inferred fields, then copy or download the source.
Open toolJSON to Swift Model Generator
Convert JSON examples into Swift model structs with nested types and optional fields. Review and download Models.swift, then add the decoding behavior your application needs.
Free to useNo sign-upRuns in your browser
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Enter the inputs, then select Generate Swift.
Your result
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Result will appear here
How JSON to Swift Model Generator works
The JSON to Swift model generator infers sample fields with quicktype and emits Swift struct definitions in its types-only configuration.
Nested objects produce additional structs, and missing or nullable sample values can produce optional properties. This configuration does not add Codable conformance or ready-to-use decoding methods. Date-like strings remain strings because date inference is disabled.
How to use JSON to Swift Model Generator
Paste a representative JSON object or object array and choose a root type name before generating the Swift definitions.
Paste representative JSON and name the root type
Include nested objects, arrays, missing fields and null values that occur in real sample records. Use an object or nonempty object array and enter the root type name in its separate field.
Input and settings
Generate Swift model structs
Run Generate Swift and inspect the structs, property names and optional markers. Read the generated definitions as types inferred from the sample rather than a complete JSON decoding implementation.
Tool result
Download Models.swift and plan decoding
Copy the source or download Models.swift. Review field types and key spelling, then add and test the Codable conformance, key mapping or other decoding code your project requires.
Review the details
Tasks for JSON to Swift Model Generator
Start Swift definitions from representative data, then check the source in your project.
Draft Swift models for an API response
Use a representative response to start Swift model definitions. Compare every field and permitted type with the actual API contract before treating the sample model as complete.
Compare optional fields across JSON records
Supply an array containing representative variations so omitted or null fields can affect inference. Include real array elements when the element type matters; an empty array cannot establish that type.
Review Swift properties and JSON key mapping
Compare generated Swift property names with the original JSON keys. Names containing punctuation can need explicit key mapping in your decoding implementation. The generated types-only structs do not supply that integration for you.
Read Swift structs and optional properties
Check the inferred properties before deciding how your project will decode the JSON.
The source contains Swift struct definitions, including nested types and optional properties where the observed samples require them. It does not conform to Codable in this configuration. A readable generated file therefore does not establish that JSONDecoder can load the original payload without further code.
Check Swift decoding needs and sample limits
Review the full API contract and your decoding approach before integrating the generated structs.
Use one JSON object or a nonempty array of objects within 100,000 characters. Choose a supported root name beginning with a letter, with at most 40 ASCII identifier characters; rejected reserved names need a different root name.
Review numeric ranges, optional fields and properties whose names differ from JSON keys. Add any required Codable conformance or custom decoding, then compile and test in your Swift project. The page does not compile the models or install dependencies.
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Open toolGenerate Swift model structs from JSON
Paste representative JSON and review the inferred Swift types before adding your project’s decoding code.
JSON to Swift Model Generator: common questions
Answers about using JSON to Swift Model Generator and understanding its results.
Does the sample define my complete API?
No. Fields and types are inferred from the sample. Review missing fields, null values and numeric ranges against your actual API contract.
Can I download the source?
Yes. Copy the generated definitions or download the source file, then review it in your project.