JSON to Swift Struct

Paste JSON and generate clean, ready-to-paste Swift Codable structs with nested models, optionals, and CodingKeys.

Root Struct Name

Protocol

Date Type

Mutable (var)

Use var instead of read-only let.

Generate CodingKeys

Map renamed keys to original JSON names.

Always emit CodingKeys

Include the enum even when no key is renamed.

Detect dates

Map ISO-8601 strings to the selected date type.

Hashable

Add Hashable conformance.

Equatable

Add Equatable conformance.

Public access

Mark structs and properties public.

Input JSON

Generated Swift

Your generated Swift structs will appear here.

About JSON to Swift Struct

This free tool turns any JSON object or array into idiomatic Swift structs that conform to Codable in one click. It inspects your JSON, infers the most specific type for every field, and generates strongly-typed models you can paste straight into an iOS, macOS, watchOS, or server-side Swift project.

It picks the right Swift type for each value — Int for whole numbers, Double for decimals, Bool, and String — and builds nested structs for inner objects and array types like [Order]. Fields that are null or only present in some array items become optionals (Type?) so decoding never fails on missing data. JSON keys in snake_case are converted to camelCase property names, and a CodingKeys enum is generated so JSONDecoder still maps to the original keys.

Choose Codable, Decodable, or Encodable conformance, add Hashable or Equatable, map ISO-8601 strings to Date, and mark everything public for framework targets. Everything runs entirely in your browser, so your JSON never leaves your device.

How to Use JSON to Swift Struct

Paste a JSON object or array into the input box, or click Load Sample to try it.
Set the root struct name for the generated model.
Pick a protocol (Codable, Decodable, or Encodable) and add Hashable / Equatable if needed.
Choose a date type, toggle let/var, CodingKeys generation, and public access to match your style.
Copy the generated Swift and paste it into your project.

Fields that are always null or hold mixed types default to String? as a safe placeholder — replace them with the correct type, or with a custom AnyCodable wrapper, if needed.

What it handles

✅ Codable structs
✅ Nested structs
✅ Optionals (Type?)
✅ Arrays as [T]
✅ CodingKeys for renamed keys
✅ snake_case → camelCase

FAQ

Does this tool send my JSON to a server?

No. All parsing and code generation happens in your browser, so your JSON stays on your device.

What is a `CodingKeys` enum and when is it added?

It tells Codable how to map Swift property names to JSON keys. The tool adds one whenever a key like created_at becomes a camelCase property such as createdAt, so decoding still finds the original key. You can also force it on for every struct.

Can I skip `CodingKeys` and use a decoder strategy instead?

Yes. Turn off Generate CodingKeys and set decoder.keyDecodingStrategy = .convertFromSnakeCase on your JSONDecoder to map snake_case automatically.

When does a property become optional?

When its value is null, or when it is missing from some objects in an array. Optional properties use the Type? syntax so decoding tolerates absent values.

Does it support root-level JSON arrays?

Yes. A root array generates a typealias Root = [Item] plus a struct for the element shape.

How do I decode dates as `Date`?

Select Date as the date type, then set a matching dateDecodingStrategy (for example .iso8601) on your JSONDecoder.