Running as a pekko-http server

To expose an endpoint as a pekko-http server, first add the following dependency:

"com.softwaremill.sttp.tapir" %% "tapir-pekko-http-server" % "1.10.1"

This will transitively pull some Pekko modules. If you want to force your own Pekko version, use sbt exclusion. Mind the Scala version in artifact name:

"com.softwaremill.sttp.tapir" %% "tapir-pekko-http-server" % "1.10.1" exclude("org.apache.pekko", "pekko-stream_2.12")

Now import the object:

import sttp.tapir.server.pekkohttp.PekkoHttpServerInterpreter

Using toRoute

The toRoute method requires a single, or a list of ServerEndpoints, which can be created by adding server logic to an endpoint.

For example:

import sttp.tapir._
import sttp.tapir.server.pekkohttp.PekkoHttpServerInterpreter
import scala.concurrent.Future
import org.apache.pekko.http.scaladsl.server.Route

def countCharacters(s: String): Future[Either[Unit, Int]] = 
  Future.successful(Right[Unit, Int](s.length))

val countCharactersEndpoint: PublicEndpoint[String, Unit, Int, Any] =[Int])
val countCharactersRoute: Route = 

Combining directives

The tapir-generated Route captures from the request only what is described by the endpoint. Combine with other pekko-http directives to add additional behavior, or get more information from the request.

For example, wrap the tapir-generated route in a metrics route, or nest a security directive in the tapir-generated directive.

Edge-case endpoints, which require special logic not expressible using tapir, can be implemented directly using pekko-http. For example:

import sttp.tapir._
import sttp.tapir.server.pekkohttp.PekkoHttpServerInterpreter
import org.apache.pekko.http.scaladsl.server._

import scala.concurrent.Future

class Special
def metricsDirective: Directive0 = ???
def specialDirective: Directive1[Special] = ???
val tapirEndpoint: PublicEndpoint[String, Unit, Unit, Any] =[String]("input"))

val myRoute: Route = metricsDirective {
  specialDirective { special =>
    PekkoHttpServerInterpreter().toRoute(tapirEndpoint.serverLogic[Future] { input => 
      /* here we can use both `special` and `input` values */


The pekko-http interpreter accepts streaming bodies of type Source[ByteString, Any], as described by the PekkoStreams capability. Both response bodies and request bodies can be streamed. Usage: streamBody(PekkoStreams)(schema, format).

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

Web sockets

The interpreter supports web sockets, with pipes of type Flow[REQ, RESP, Any]. See web sockets for more details.

pekko-http does not expose control frames (Ping, Pong and Close), so any setting regarding them are discarded, and ping/pong frames which are sent explicitly are ignored. Automatic pings can be instead enabled through configuration.

Server Sent Events

The interpreter supports SSE (Server Sent Events).

For example, to define an endpoint that returns event stream:

import sttp.model.sse.ServerSentEvent
import sttp.tapir._
import sttp.tapir.server.pekkohttp.{PekkoHttpServerInterpreter, serverSentEventsBody}

import scala.concurrent.Future

val sseEndpoint = endpoint.get.out(serverSentEventsBody)

val routes = PekkoHttpServerInterpreter().toRoute(sseEndpoint.serverLogicSuccess[Future](_ =>
  Future.successful(Source.single(ServerSentEvent(Some("data"), None, None, None)))


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