A really fast JSON library

What's New


Decoding arrays


A simple, yet fast JSON library. Developed for the OpenKitten ecosystem, it is created to feel like it belongs to the ecosystem as well as the programming language.

Cheetah's aim is to be a performant parser/serializer and to provide a good API.


Import this dependency into your Package.swift

.Package(url: "", majorVersion: 1)

Deserialize from UTF-8 bytes representing a JSON String:

let array = JSONArray(from: bytes)
let object = JSONObject(from: bytes)

Deserialize from a Swift String JSON:

let array = JSONArray(from: bytes)
let object = JSONObject(from: bytes)

Access values in an array like you would in Swift Arrays and values in an object like a Dictionary.

let favouriteNumber = favouriteNumbers[0]
let usernameValue = userObject["username"]

Extract types with simplicity:

let username = String(userObject["username"]) // "Joannis"
let isOnline = Bool(userObject["online"]) // true
let age = Int(userObject["age"]) // 20
let pi = Double(userObject["pi_constant"]) // 3.14

Chain subscripts easily to find results without a hassle as shown underneath:

  "users": [
  		"username": "Joannis",
  		"profile": {
  		  "firstName": "Joannis",
  		  "lastName": "Orlandos"
  		"username": "Obbut",
  		"profile": {
  		  "firstName": "Robbert",
  		  "lastName": "Brandsma"
let obbutLastName = String(object["users"][1]["profile"]["lastName"]) // "Brandsma"


Tutorials and docs are available among the rest.


  • Swift Tools 3.0.0
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Last updated: Thu Mar 23 2023 01:24:27 GMT-0500 (GMT-05:00)