❄️ Bifrost

Bifrost is a typed JSON HTTP client for Swift, built around Encodable request models and Decodable responses.

An API describes shared transport configuration. Each request describes its path, method, inputs, and response type. Bifrost turns the two into a URLRequest, runs an interception pipeline, and returns the decoded value.

• Derive query items or JSON bodies from request properties.
• Decode each endpoint into its own response type with async/await.
• Customize sessions, JSON coding, shared query items, and request headers.
• Mutate, mock, recover, or restart calls with ordered interceptors.
• Trace request lifecycles with privacy-conscious diagnostic levels.

let posts = try await PostsAPI().response(
  for: PostsForUser(userId: 1)
)

Install

Bifrost supports iOS 17 and later and macOS 11 and later. It requires a Swift 6.2 toolchain and is distributed through Swift Package Manager.

Add the package dependency:

dependencies: [
  .package(url: "https://github.com/mtzaquia/bifrost.git", from: "3.0.5"),
]

Add the Bifrost product to the consuming target, then import Bifrost where it is used. In Xcode, enter https://github.com/mtzaquia/bifrost.git in File → Add Package Dependencies.

Five-minute start

The following request loads posts for one user. Because PostsForUser uses the default GET method, Bifrost encodes userId as a query item and requests https://jsonplaceholder.typicode.com/posts?userId=1.

import Bifrost
import Foundation

struct Post: Decodable, Sendable {
  let id: Int
  let title: String
  let body: String
}

struct PostsForUser: Requestable, Sendable {
  let userId: Int

  var path: String { "posts" }

  typealias Response = [Post]
}

struct PostsAPI: API {
  let baseURL = URL(
    string: "https://jsonplaceholder.typicode.com"
  )!
}

func loadPosts() async throws -> [Post] {
  try await PostsAPI().response(
    for: PostsForUser(userId: 1)
  )
}

That is the core idea: model an endpoint as a value, associate it with the response it expects, and pass it to an API configuration.

Documentation

• Getting started — configure an API, model an endpoint, and perform the first request.
• Requests and responses — control paths, methods, parameters, headers, coding, transport, and failures.
• Interceptors — mutate requests, provide mock responses, transform raw responses, and restart recovery flows.
• Diagnostics — inspect request lifecycles without exposing sensitive details by default.

License

Copyright (c) 2025 @mtzaquia

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.