Open Source Scala HTTP Clients

sttp client is an open-source library that provides a clean, programmer-friendly API to describe HTTP requests and how to handle responses. Requests are sent using one of the backends, which wrap other Scala or Java HTTP client implementations. The backends can integrate with a variety of Scala stacks, providing both synchronous and asynchronous, procedural and functional interfaces. Backend implementations include ones based on akka-http, http4s, OkHttp, and HTTP clients which ship with Java. They integrate with Akka, Monix, fs2, cats-effect, scalaz and ZIO. Supported Scala versions include 2.11, 2.12, 2.13 and 3, Scala.JS and Scala Native.

Finch is a thin layer of purely functional basic blocks atop of Finagle for building composable HTTP APIs. Its mission is to provide the developers with simple and robust HTTP primitives being as close as possible to the bare metal Finagle API.

Http4s is a minimal, idiomatic Scala interface for HTTP services. Http4s is Scala's answer to Ruby's Rack, Python's WSGI, Haskell's WAI, and Java's Servlets. http4s servers and clients share an immutable model of requests and responses. Standard headers are modeled as semantic types, and entity codecs are done by typeclass. The pure functional side of Scala is favored to promote composability and easy reasoning about your code. I/O is managed through cats-effect. http4s is built on FS2, a streaming library that provides for processing and emitting large payloads in constant space and implementing websockets. http4s cross-builds for Scala.js and Scala Native. Share code and deploy to browsers, Node.js, native executable binaries, and the JVM.

Simple scala wrapper for HttpURLConnection. OAuth included. This is a fully featured http client for Scala which wraps java.net.HttpURLConnection. The library is thread safe. HttpRequest and HttpResponse are immutable. So it should be easy to wrap in an execution framework of your choice. If you're including this in some other public library. Do your users a favor and change the fully qualified name so they don't have version conflicts if they're using a different version of this library. The easiest way to do that is just to copy the source into your project.

Elastic4s is a concise, idiomatic, reactive, type safe Scala client for Elasticsearch. The official Elasticsearch Java client can of course be used in Scala, but due to Java's syntax it is more verbose and it naturally doesn't support classes in the core Scala core library nor Scala idioms such as typeclass support. Elastic4s's DSL allows you to construct your requests programatically, with syntactic and semantic errors manifested at compile time, and uses standard Scala futures to enable you to easily integrate into an asynchronous workflow. The aim of the DSL is that requests are written in a builder-like way, while staying broadly similar to the Java API or Rest API. Each request is an immutable object, so you can create requests and safely reuse them, or further copy them for derived requests. Because each request is strongly typed your IDE or editor can use the type information to show you what operations are available for any request type.