About JSON → Swift Struct

Generate a Codable Swift struct from a JSON sample. Part of the DevTools Surf developer suite. Browse more tools in the Converters collection.

Use Cases

• iOS developers modeling REST API responses as structs
• Swift backend engineers parsing JSON payloads in Vapor
• Mobile teams migrating from manual JSON parsing to Codable
• Cross-platform developers sharing data models between iOS and macOS

Tips

• Paste nested JSON to generate nested Codable structs automatically
• Use optional fields for keys that may be null in your API responses
• Check the generated CodingKeys enum for snake_case to camelCase mapping

Fun Facts

• Swift's Codable protocol was introduced in Swift 4 (2017), replacing the verbose NSJSONSerialization API that required manual key-path extraction.
• The name 'Swift' was chosen by Chris Lattner partly because swifts are fast birds — the white-throated needletail can reach speeds of 170 km/h.
• Before Codable, most iOS developers relied on third-party libraries like SwiftyJSON or ObjectMapper, which collectively had over 40,000 GitHub stars.

FAQ

Is it Codable?

Yes — every struct conforms to `Codable` (both Encodable and Decodable). Ready to drop into `JSONEncoder()`/`JSONDecoder()` without further setup.

How are optional fields handled?

Fields not present in every sample record are marked optional (`String?`). For explicit nil support, the generated decoder respects both missing-key and null-value cases.

What about CodingKeys?

Auto-generated `CodingKeys` enum when JSON keys don't match Swift naming conventions (e.g. snake_case JSON → camelCase Swift).

SwiftUI-compatible?

Yes — the output is plain Swift with no SwiftUI imports. Works in UIKit, SwiftUI, server-side Swift (Vapor), or iOS command-line tools.