Code Quality Rank: L4
Monthly Downloads: 0
Programming language: Swift
License: MIT License
Tags: JSON    
Latest version: v1.0.1

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Pure-Swift JSON parser & formatter. Fully streamable input and output. Linux & OS X ready. Replacement for NSJSONSerialization.

Jay conforms to the following specifications:

For extra convenience functions when working with the JSON enum, check out Jay-Extras.

:question: Why?

We all use JSON. Especially when writing server-side Swift that needs to run on Linux. #0dependencies

This is my take on how a JSON parser should work. This is not another JSON mapping utility library. This is an actual JSON parser and formatter. Check out the code, it was fun to write 😇


  • [x] Parsing: data -> JSON object
  • [x] Formatting: JSON object -> data
  • [x] Pretty printing
  • [x] Streaming input and output, low memory footprint


Parsing from data (deserialization)

do {
    //get data from disk/network
    let data: [UInt8] = ...

    //ask Jay to parse your data
    let json = try Jay().jsonFromData(data) // JSON
    let json = try Jay().anyJsonFromData(data) // [String: Any] or [Any]

    //if it doesn't throw an error, all went well
    if let tasks = json.dictionary?["today"]?.array {
        //you have a dictionary root object, with an array under the key "today"
        print(tasks) //["laundry", "cook dinner for gf"]
} catch {
    print("Parsing error: \(error)")

Formatting into data (serialization)

do {
    //get a json object (works for both [String: Any] and typesafe versions - JSON)

    //ask Jay to generate data
    let anyContainer = ... // [String: Any] or [Any]
    let data = try Jay(formatting: .prettified).dataFromJson(any: json) // [UInt8]
    let json: JSON = ... // JSON
    let data = try Jay(formatting: .prettified).dataFromJson(json: json) // [UInt8]

    //send data over network, save to disk
} catch {
    print("Formatting error: \(error)")


Swift Package Manager

.Package(url: "https://github.com/czechboy0/Jay.git", majorVersion: 1)

:blue_heart: Code of Conduct

Please note that this project is released with a [Contributor Code of Conduct](./CODE_OF_CONDUCT.md). By participating in this project you agree to abide by its terms.

:gift_heart: Contributing

Please create an issue with a description of your problem or open a pull request with a fix.

:v: License


:alien: Author

Honza Dvorsky - http://honzadvorsky.com, @czechboy0

*Note that all licence references and agreements mentioned in the Jay README section above are relevant to that project's source code only.