diff --git a/conf/base.conf b/conf/base.conf
index ddf79f02ee40..5a1706d57c53 100644
--- a/conf/base.conf
+++ b/conf/base.conf
@@ -545,6 +545,7 @@ challenge {
   history.message.ttl = 30 seconds
   uid.timeout = 7 seconds
   max_playing = ${setup.max_playing}
+  net.base_url = ${net.base_url}
 }
 evalCache {
   collection.eval_cache = eval_cache
diff --git a/modules/challenge/src/main/Env.scala b/modules/challenge/src/main/Env.scala
index 64fb7f63ed4c..a5520b0664dd 100644
--- a/modules/challenge/src/main/Env.scala
+++ b/modules/challenge/src/main/Env.scala
@@ -31,6 +31,7 @@ final class Env(
     val UidTimeout = config duration "uid.timeout"
     val SocketTimeout = config duration "socket.timeout"
     val MaxPlaying = config getInt "max_playing"
+    val NetBaseUrl = config getString "net.base_url"
   }
   import settings._
 
@@ -79,7 +80,7 @@ final class Env(
     maxPerUser = MaxPerUser
   )
 
-  lazy val jsonView = new JsonView(lightUser, isOnline)
+  lazy val jsonView = new JsonView(lightUser, isOnline, NetBaseUrl)
 
   scheduler.future(3 seconds, "sweep challenges") {
     api.sweep
diff --git a/modules/challenge/src/main/JsonView.scala b/modules/challenge/src/main/JsonView.scala
index be0796b000e0..2fb30d9f0bd9 100644
--- a/modules/challenge/src/main/JsonView.scala
+++ b/modules/challenge/src/main/JsonView.scala
@@ -9,7 +9,8 @@ import lidraughts.socket.UserLagCache
 
 final class JsonView(
     getLightUser: lidraughts.common.LightUser.GetterSync,
-    isOnline: lidraughts.user.User.ID => Boolean
+    isOnline: lidraughts.user.User.ID => Boolean,
+    baseUrl: String
 ) {
 
   import lidraughts.game.JsonView._
@@ -28,6 +29,7 @@ final class JsonView(
 
   def apply(direction: Option[Direction])(c: Challenge): JsObject = Json.obj(
     "id" -> c.id,
+    "url" -> s"$baseUrl/${c.id}",
     "status" -> c.status.name,
     "challenger" -> c.challengerUser,
     "destUser" -> c.destUser,