Server-side Swift. The Perfect library, application server, connectors and example apps. (For mobile back-end development, website and web app development, and more...)


Perfect: Server-Side Swift

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Swift 3.0 Platforms OS X | Linux License Apache Docs GitHub issues codebeat Twitter Join the chat at

The master branch of this project currently compiles with the default Swift 3.0 toolchain included in Xcode 8 beta 2. On Ubuntu use the DEVELOPMENT-SNAPSHOT-2016-06-20-a toolchain, released June 20th.

Important: On OS X you must set the Xcode command line tools preference as follows: Xcode Prefs

If you do not do this you will experience compile time errors when using SPM on the command line.

If you are still having build problems with any of the code in our repositories, try doing a clean build with Swift Package Manager by typing:

swift build --clean=dist ; swift build

Perfect is an application server for Linux or OS X which provides a framework for developing web and other REST services in the Swift programming language. Its primary focus is on facilitating mobile apps which require backend server software, enabling you to use one language for both front and back ends.

Perfect operates using either its own stand-alone HTTP/HTTPS server or through FastCGI. It provides a system for loading your own Swift based modules at startup and for interfacing those modules with its request/response objects or to the built-in mustache template processing system.

Perfect is built on its own high performance completely asynchronous networking engine with the goal of providing a scalable option for internet services. It supports SSL out of the box and provides a suite of tools which are commonly required by internet servers, such as WebSockets and iOS push notifications, but does not limit your options. Feel free to swap in your own favorite JSON or templating systems, etc.

Quick Start

Swift 3.0

Ensure you have properly installed a Swift 3.0 toolchain from In the terminal, typing:

swift --version

should produce something like the following:

Apple Swift version 3.0 (swiftlang-800.0.33.1 clang-800.0.31)
Target: x86_64-apple-macosx10.9


Perfect relies on Home Brew for installing dependencies on OS X. This is currently limited to OpenSSL. To install Home Brew, in the Terminal, type:

/usr/bin/ruby -e "$(curl -fsSL"

To install OpenSSL:

brew install openssl
brew link openssl --force


Perfect relies on OpenSSL, libssl-dev and uuid:

sudo apt-get install openssl libssl-dev uuid-dev

Build Starter Project

The following will clone and build an empty starter project and launch the server on port 8181.

git clone
cd PerfectTemplate
swift build

You should see the following output:

Starting HTTP server on with document root ./webroot

This means the server is running and waiting for connections. Access http://localhost:8181/ to see the greeting. Hit control-c to terminate the server.

You can view the full source code for PerfectTemplate.


Swift Package Manager can generate an Xcode project which can run the PerfectTemplate server and provide full source code editing and debugging for your project. Enter the following in your terminal:

swift package generate-xcodeproj

Open the generated file "PerfectTemplate.xcodeproj". Ensure that you have selected the executable target and selected it to run on "My Mac". You can now run and debug the server.

Next Steps

These example snippets show how to accomplish several common tasks that one might need to do when developing a Web/REST application. In all cases, the request and response variables refer, respectively, to the HTTPRequest and HTTPResponse objects which are given to your URL handlers.

Consult the API reference for more details.

Get a client request header

if let acceptEncoding = request.header(.acceptEncoding) {

Get client GET or POST parameters

if let foo = request.param(name: "foo") {
if let foo = request.param(name: "foo", defaultValue: "default foo") {
let foos: [String] = request.params(named: "foo")

Get the current request path

let path = request.path

Access the server's document directory and return an image file to the client

let docRoot = request.documentRoot
do {
    let mrPebbles = File("\(docRoot)/mr_pebbles.jpg")
    let imageSize = mrPebbles.size
    let imageBytes = try mrPebbles.readSomeBytes(count: imageSize)
    response.setHeader(.contentType, value: MimeType.forExtension("jpg"))
    response.setHeader(.contentLength, value: "\(imageBytes.count)")
    response.appendBody(bytes: imageBytes)
} catch {
    response.status = .internalServerError
    response.appendBody(string: "Error handling request: \(error)")

Get client cookies

for (cookieName, cookieValue) in request.cookies {

Set client cookie

let cookie = HTTPCookie(name: "cookie-name", value: "the value", domain: nil,
                    expires: .session, path: "/",
                    secure: false, httpOnly: false)

Return JSON data to client

response.setHeader(.contentType, value: "application/json")
let d: [String:Any] = ["a":1, "b":0.1, "c": true, "d":[2, 4, 5, 7, 8]]

do {
    try response.setBody(json: d)
} catch {

This snippet uses the built-in JSON encoding. Feel free to bring in your own favorite JSON encoder/decoder.

Repository Layout

We have finished refactoring Perfect to support Swift Package Manager. The Perfect project has been split up into the following repositories:

  • Perfect - This repository contains the core PerfectLib and will continue to be the main landing point for the project.
  • PerfectTemplate - A simple starter project which compiles with SPM into a stand-alone executable HTTP server. This repository is ideal for starting on your own Perfect based project.
  • PerfectDocs - Contains all API reference related material.
  • PerfectExamples - All the Perfect example projects and documentation.
  • PerfectTemplateFCGI - A simple starter project which compiles with SPM into a FastCGI server suitable for use with Apache 2.4 or NGINX. This repository is ideal for starting on your own Perfect based project if you are required to use an existing server which supports FastCGI.
  • Perfect-Redis - Redis database connector.
  • Perfect-SQLite - SQLite3 database connector.
  • Perfect-PostgreSQL - PostgreSQL database connector.
  • Perfect-MySQL - MySQL database connector.
  • Perfect-MongoDB - MongoDB database connector.
  • Perfect-FastCGI-Apache2.4 - Apache 2.4 FastCGI module; required for the Perfect FastCGI server variant.

The database connectors are all stand-alone and can be used outside of the Perfect framework and server.

Further Information

For more information on the Perfect project, please visit