JSON to Swift

Paste a JSON sample and get Codable Swift structs with nested types, optionals and ready made CodingKeys.

Generate Codable structs from JSON

Root struct name Optionals

JSON sample

Structs: 0 · Properties: 0 · Lines: 0

Paste a JSON object or array and press Generate Swift.

Types are inferred from the sample and merged across array elements, so a key that is a number in one element and a string in another becomes String.

Paste a JSON object or array into the sample box, or press Load sample to try one.
Set the root struct name and choose how optionals should be handled.
Press Generate Swift and copy the structs, then decode with JSONDecoder in your app.

Common questions about the free online json to swift.

Paste a JSON sample, set the root struct name and press Generate Swift to get Codable structs you can paste into Xcode.

Yes. Nested JSON objects and arrays of objects each become their own struct, named after the key that holds them.

A property becomes optional when the sample value is null, or when array elements disagree about the key.

If a JSON key is snake case or not a valid Swift name, a CodingKeys enum maps the Swift property to the original key.

Numbers become Double, true and false become Bool, text becomes String, arrays become Swift arrays and objects become structs.

Use JSONDecoder and decode the root type, as shown in the comment at the end of the generated code.

The sample alone cannot tell an integer from a decimal, so Double is used and you can change it to Int where you know better.

An empty array gives an array of String, which you can change once you know what the elements really are.

Yes. It is free, runs entirely in your browser and never sends your JSON sample to a server.

Last updated: October 10, 2026