JSON to Swift Struct
LiveGenerate Swift Codable struct definitions from JSON data.
Understanding JSON (JavaScript Object Notation)
Swift's Codable protocol provides a type-safe way to parse JSON in iOS, macOS, tvOS, and watchOS applications. Swift structs conforming to Codable can be decoded from JSON using JSONDecoder and encoded back using JSONEncoder. Converting JSON to Swift structs with Codable conformance generates the boilerplate code needed for Apple platform API integration — property declarations, CodingKeys enums for key mapping, and nested type definitions.
Convert JSON data to Swift structs conforming to the Codable protocol. Generates proper Swift types with CodingKeys enum for JSON key mapping, handles nested objects, optional values, and arrays. Produces clean Swift 5+ code ready for Xcode and iOS/macOS development.
The Devkitr JSON to Swift Struct Converter generates Swift struct definitions conforming to Codable from JSON data. Paste API response JSON to get Swift structs with let properties, CodingKeys enums, Optional types for nullable fields, and nested struct definitions — ready for JSONDecoder.
In a typical development workflow, JSON to Swift Struct becomes valuable whenever you need to generate swift codable struct definitions from json data. Whether you are working on a personal side project, maintaining production applications for a company, or collaborating with a distributed team across time zones, having a reliable browser-based conversion tool eliminates the need to install desktop software, write one-off scripts, or send data to third-party services that may log or retain your information. Since JSON to Swift Struct processes everything locally on your device, your data stays private and your workflow stays uninterrupted — open a browser tab, paste your input, get your result.
Key Features
Codable Conformance
Generates structs conforming to Codable (Decodable + Encodable) for direct use with JSONDecoder and JSONEncoder.
CodingKeys Generation
Creates CodingKeys enum when JSON keys differ from Swift naming conventions (snake_case JSON → camelCase Swift).
Swift Type Mapping
Maps JSON types to Swift types: String, Int, Double, Bool, [T] for arrays, and Optional<T> for nullable values.
Nested Struct Types
Creates nested struct definitions for JSON objects within objects, organized as inner types or separate top-level structs.
How to Use JSON to Swift Struct
Paste JSON Data
Enter JSON from your API, backend service, or any data source your Swift application consumes.
Configure Options
Choose between inner nested structs or top-level structs, and select whether to generate CodingKeys enums.
Review Swift Structs
Verify property types, Optional annotations, CodingKeys mappings, and nested type definitions.
Copy Swift Code
Copy the struct definitions into your Xcode project for JSON parsing in your iOS/macOS application.
Use Cases
iOS REST API Integration
Generate Codable structs for URLSession or Alamofire JSON response parsing in iOS applications.
SwiftUI Data Models
Create model types for SwiftUI views that are loaded from JSON APIs using async/await and JSONDecoder.
Vapor Server-Side Models
Generate Content-conforming structs for Vapor (server-side Swift) API request and response models.
Core Data JSON Mapping
Create intermediate Codable structs for mapping JSON API responses to Core Data managed object attributes.
Pro Tips
Use let properties (immutable) in Codable structs — decoded data should be immutable to prevent accidental modification.
Set JSONDecoder.keyDecodingStrategy = .convertFromSnakeCase to avoid manual CodingKeys when all JSON keys use snake_case.
Use Optional<T> for fields that may be absent or null in JSON responses — this prevents decoding failures from missing data.
For date fields, configure JSONDecoder.dateDecodingStrategy instead of handling date strings manually in each model.
Common Pitfalls
Making all properties non-optional without verifying the API always returns them
Fix: Non-optional properties cause JSONDecoder to throw if the field is missing. Use Optional for fields the API might omit.
Not using CodingKeys for snake_case JSON keys
Fix: JSON "first_name" does not auto-map to Swift firstName. Use CodingKeys enum or set .convertFromSnakeCase on the decoder.
Using classes instead of structs for Codable types
Fix: Swift structs are preferred for Codable — they are value types with automatic Equatable conformance and no reference-counting overhead.
Frequently Asked Questions
QDoes it use Codable protocol?
Yes. All generated structs conform to Codable (Encodable & Decodable) for seamless JSON parsing with JSONDecoder.
QAre CodingKeys generated?
Yes. A CodingKeys enum is included when JSON key names differ from Swift property naming conventions.
QDoes it handle optional values?
Yes. JSON null values generate Optional types (String?) in the Swift output.
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