Running as a zio-http server

The tapir-zio module defines type aliases and extension methods which make it more ergonomic to work with ZIO and tapir. Moreover, tapir-zio-http-server contains an interpreter useful when exposing the endpoints using the ZIO Http server.

You’ll need the following dependency for the ZServerEndpoint type alias and helper classes:

"com.softwaremill.sttp.tapir" %% "tapir-zio" % "0.19.0-M13"

or just add the zio-http integration which already depends on tapir-zio:

"com.softwaremill.sttp.tapir" %% "tapir-zio-http" % "0.19.0-M13"

Next, instead of the usual import sttp.tapir._, you should import (or extend the ZTapir trait, see MyTapir):

import sttp.tapir.ztapir._

This brings into scope all of the basic input/output descriptions, which can be used to define an endpoint.


You should have only one of these imports in your source file. Otherwise, you’ll get naming conflicts. The import sttp.tapir.ztapir._ import is meant as a complete replacement of import sttp.tapir._.

Exposing endpoints

import sttp.tapir.server.ziohttp.ZioHttpInterpreter

The ZioHttpInterpreter objects contains methods: toHttp and toHttpRecoverErrors.

The toHttp method requires a ZServerEndpoint (see below), or that the logic of the endpoint is given as a function of type:

I => ZIO[R, E, O]

For example:

import sttp.tapir._
import sttp.tapir.server.ziohttp.ZioHttpInterpreter
import zhttp.http.{Http, Request, Response}
import zio._

def countCharacters(s: String): ZIO[Any, Nothing, Int] =

val countCharactersEndpoint: Endpoint[String, Unit, Int, Any] =[Int])
val countCharactersHttp: Http[Any, Throwable, Request, Response[Any, Throwable]]  =

Note that the second argument to toHttp is a function with one argument, a tuple of type I. This means that functions which take multiple arguments need to be converted to a function using a single argument using .tupled:

import sttp.tapir._
import sttp.tapir.server.ziohttp.ZioHttpInterpreter
import zhttp.http.{Http, Request, Response}
import zio._

def logic(s: String, i: Int): ZIO[Any, Nothing, String] = ???
val anEndpoint: Endpoint[(String, Int), Unit, String, Any] = ???
val anHttp: Http[Any, Throwable, Request, Response[Any, Throwable]] = 
    ZioHttpInterpreter().toHttp(anEndpoint)((logic _).tupled)

Server logic

When defining the business logic for an endpoint, the following methods are available, which replace the standard ones:

  • def zServerLogic(logic: I => ZIO[R, E, O]): ZServerEndpoint[R, I, E, O, C]
  • def zServerLogicPart(logicPart: T => ZIO[R, E, U])
  • def zServerLogicForCurrent(logicPart: I => ZIO[R, E, U])

The first defines complete server logic, while the second and third allow defining server logic in parts.


The zio-http interpreter accepts streaming bodies of type Stream[Throwable, Byte], as described by the ZioStreams capability. Both response bodies and request bodies can be streamed. Usage: streamBody(ZioStreams)(schema, format).

The capability can be added to the classpath independently of the interpreter through the "com.softwaremill.sttp.shared" %% "zio" dependency.


The interpreter can be configured by providing an ZioHttpServerOptions value, see server options for details.

Defining an endpoint together with the server logic

It’s also possible to define an endpoint together with the server logic in a single, more concise step. See server logic for details.