cats, http, scala, akka-http, asynchronous, uri, reactive-streams, httpclient, okhttp, scalaz, synchronous, monix, zipkin, distributed-tracing, interpolator, zipkin-brave



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The Scala HTTP client that you always wanted!


sttp client is an open-source library which 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, async-http-client, http4s, OkHttp, and HTTP clients which ship with Java. They integrate with Akka, Monix, fs2, cats-effect, scalaz and ZIO.

Here's a very quick example of sttp client in action:

import sttp.client._

val sort: Option[String] = None
val query = "http language:scala"

// the `query` parameter is automatically url-encoded
// `sort` is removed, as the value is not defined
val request = basicRequest.get(uri"$query&sort=$sort")
implicit val backend = HttpURLConnectionBackend()
val response = request.send()

// response.header(...): Option[String]

// response.body: by default read into an Either[String, String] to indicate failure or success 

// alternatively, if you prefer to pass the backend explicitly, instead
// of using implicits, you can also call:
val sameResponse = backend.send(request)                      


sttp (v2) documentation is available at

sttp (v1) documentation is available at

scaladoc is available at

Quickstart with Ammonite

If you are an Ammonite user, you can quickly start experimenting with sttp by copy-pasting the following:

import $ivy.`com.softwaremill.sttp.client::core:2.2.1`
import sttp.client.quick._

This brings in the sttp API and an implicit, synchronous backend.

Quickstart with sbt

Add the following dependency:

"com.softwaremill.sttp.client" %% "core" % "2.2.1"

Then, import:

import sttp.client._

Type sttp. and see where your IDE’s auto-complete gets you!

Other sttp projects

sttp is a family of Scala HTTP-related projects, and currently includes:

  • sttp client: this project
  • sttp tapir: Typed API descRiptions
  • sttp model: simple HTTP model classes (used by client & tapir)


If you have a question, or hit a problem, feel free to ask on our gitter channel!

Or, if you encounter a bug, something is unclear in the code or documentation, don’t hesitate and open an issue on GitHub.

We are also always looking for contributions and new ideas, so if you’d like to get into the project, check out the open issues, or post your own suggestions!

Testing the Scala.JS backend

Running the tests using the JS backend has some prerequisities:

Note that running the default test task will run the tests using both the JVM and JS backends. If you'd like to run the tests using only the JVM backend, execute: sbt rootJVM/test.

Building & testing the scala-native backend

By default, sttp-native will not be included in the aggregate build of the root project. To include it, define the STTP_NATIVE environmental variable before running sbt, e.g.:


You might need to install some additional libraries, see the scala native documentation site. On macos, you might additionally need:

ln -s /usr/local/opt/openssl/lib/libcrypto.dylib /usr/local/lib/
ln -s /usr/local/opt/openssl/lib/libssl.dylib /usr/local/lib/

Commercial Support

We offer commercial support for sttp and related technologies, as well as development services. Contact us to learn more about our offer!


Copyright (C) 2017-2020 SoftwareMill