diff --git a/modules/api/src/main/Env.scala b/modules/api/src/main/Env.scala
index abea50f373..313e442a28 100644
--- a/modules/api/src/main/Env.scala
+++ b/modules/api/src/main/Env.scala
@@ -7,7 +7,9 @@ import play.api.{ Configuration, Mode }
 import scala.concurrent.duration._
 
 import lila.common.config._
+import lila.common.Bus
 import lila.user.User
+import lila.chat.GetLinkCheck
 
 @Module
 final class Env(
@@ -55,6 +57,7 @@ final class Env(
 
   val config = ApiConfig loadFrom appConfig
   import config.apiToken
+  import net.domain
 
   lazy val pgnDump: PgnDump = wire[PgnDump]
 
@@ -85,6 +88,12 @@ final class Env(
   )
   if (mode == Mode.Prod) system.scheduler.scheduleOnce(5 seconds)(influxEvent.start())
 
+  private lazy val linkCheck = wire[LinkCheck]
+
+  Bus.subscribeFun("chatLinkCheck") {
+    case GetLinkCheck(line, source, promise) => promise completeWith linkCheck(line, source)
+  }
+
   system.scheduler.scheduleWithFixedDelay(1 minute, 1 minute) { () =>
     lila.mon.bus.classifiers.update(lila.common.Bus.size)
     // ensure the Lichess user is online
diff --git a/modules/api/src/main/LinkCheck.scala b/modules/api/src/main/LinkCheck.scala
new file mode 100644
index 0000000000..56adcf04f6
--- /dev/null
+++ b/modules/api/src/main/LinkCheck.scala
@@ -0,0 +1,130 @@
+package lila.api
+
+import cats.implicits._
+import scala.concurrent.ExecutionContext
+
+import lila.chat.UserLine
+import lila.common.config.NetDomain
+import lila.hub.actorApi.shutup.PublicSource
+import lila.simul.Simul
+import lila.simul.SimulApi
+import lila.swiss.Swiss
+import lila.swiss.SwissApi
+import lila.team.Team
+import lila.team.TeamRepo
+import lila.tournament.Tournament
+import lila.tournament.TournamentRepo
+import lila.user.User
+import lila.study.Study
+import lila.study.StudyRepo
+
+/* Determine if a link to a lichess resource
+ * can be posted from another lichess resource.
+ * Owners of a resource can post any link on it (but not to it).
+ * Links to a team resource can be posted from another resource of the same team.
+ * Links to official resources can be posted from anywhere.
+ * */
+final private class LinkCheck(
+    domain: NetDomain,
+    teamRepo: TeamRepo,
+    tournamentRepo: TournamentRepo,
+    simulApi: SimulApi,
+    swissApi: SwissApi,
+    studyRepo: StudyRepo
+)(implicit ec: ExecutionContext) {
+
+  import LinkCheck._
+
+  def apply(line: UserLine, source: PublicSource): Fu[Boolean] = {
+    if (multipleLinks find line.text) fuFalse
+    else
+      line.text match {
+        case tournamentLinkR(id) => withSource(source, tourLink)(id, line)
+        case simulLinkR(id)      => withSource(source, simulLink)(id, line)
+        case swissLinkR(id)      => withSource(source, swissLink)(id, line)
+        case studyLinkR(id)      => withSource(source, studyLink)(id, line)
+        case _                   => fuTrue
+      }
+  }
+
+  private def withSource(
+      source: PublicSource,
+      f: (String, FullSource) => Fu[Boolean]
+  )(id: String, line: UserLine): Fu[Boolean] = {
+    source match {
+      case PublicSource.Tournament(id) => tournamentRepo byId id map2 FullSource.TournamentSource
+      case PublicSource.Simul(id)      => simulApi find id map2 FullSource.SimulSource
+      case PublicSource.Swiss(id)      => swissApi byId Swiss.Id(id) map2 FullSource.SwissSource
+      case PublicSource.Team(id)       => teamRepo byId id map2 FullSource.TeamSource
+      case PublicSource.Study(id)      => studyRepo byId Study.Id(id) map2 FullSource.StudySource
+      case _                           => fuccess(none)
+    }
+  } flatMap {
+    _ ?? { source =>
+      // the owners of a chat can post whichever link they like
+      if (source.owners(line.userId)) fuTrue
+      else f(id, source)
+    }
+  }
+
+  private def tourLink(tourId: Tournament.ID, source: FullSource) =
+    tournamentRepo byId tourId flatMap {
+      _ ?? { tour =>
+        fuccess(tour.isScheduled) >>| {
+          source.teamId ?? { sourceTeamId =>
+            fuccess(tour.conditions.teamMember.exists(_.teamId == sourceTeamId)) >>|
+              tournamentRepo.isForTeam(tour.id, sourceTeamId)
+          }
+        }
+      }
+    }
+
+  private def simulLink(simulId: Tournament.ID, source: FullSource) =
+    simulApi teamOf simulId map {
+      _ exists source.teamId.has
+    }
+
+  private def swissLink(swissId: String, source: FullSource) =
+    swissApi teamOf Swiss.Id(swissId) map {
+      _ exists source.teamId.has
+    }
+
+  private def studyLink(studyId: String, source: FullSource) = fuFalse
+
+  private val multipleLinks   = s"$domain.+$domain".r.unanchored
+  private val tournamentLinkR = s"$domain/tournament/(\\w+)".r.unanchored
+  private val simulLinkR      = s"$domain/simul/(\\w+)".r.unanchored
+  private val swissLinkR      = s"$domain/swiss/(\\w+)".r.unanchored
+  private val studyLinkR      = s"$domain/study/(\\w+)".r.unanchored
+}
+
+private object LinkCheck {
+
+  sealed trait FullSource {
+    def owners: Set[User.ID]
+    def teamId: Option[Team.ID]
+  }
+
+  object FullSource {
+    case class TournamentSource(value: Tournament) extends FullSource {
+      def owners = Set(value.createdBy)
+      def teamId = value.conditions.teamMember.map(_.teamId)
+    }
+    case class SimulSource(value: Simul) extends FullSource {
+      def owners = Set(value.hostId)
+      def teamId = value.team
+    }
+    case class SwissSource(value: Swiss) extends FullSource {
+      def owners = Set(value.createdBy)
+      def teamId = value.teamId.some
+    }
+    case class TeamSource(value: Team) extends FullSource {
+      def owners = value.leaders
+      def teamId = value.id.some
+    }
+    case class StudySource(value: Study) extends FullSource {
+      def owners = value.members.idSet
+      def teamId = none
+    }
+  }
+}
diff --git a/modules/chat/src/main/ChatApi.scala b/modules/chat/src/main/ChatApi.scala
index 74fd524528..e54f8f6044 100644
--- a/modules/chat/src/main/ChatApi.scala
+++ b/modules/chat/src/main/ChatApi.scala
@@ -4,9 +4,9 @@ import chess.Color
 import reactivemongo.api.ReadPreference
 import scala.concurrent.duration._
 
+import lila.common.Bus
 import lila.common.config.NetDomain
 import lila.common.String.noShouting
-import lila.common.Bus
 import lila.db.dsl._
 import lila.hub.actorApi.shutup.{ PublicSource, RecordPrivateChat, RecordPublicChat }
 import lila.memo.CacheApi._
@@ -23,7 +23,7 @@ final class ChatApi(
     cacheApi: lila.memo.CacheApi,
     maxLinesPerChat: Chat.MaxLines,
     netDomain: NetDomain
-)(implicit ec: scala.concurrent.ExecutionContext) {
+)(implicit ec: scala.concurrent.ExecutionContext, actorSystem: akka.actor.ActorSystem) {
 
   import Chat.{ chatIdBSONHandler, userChatBSONHandler }
 
@@ -88,20 +88,31 @@ final class ChatApi(
     ): Funit =
       makeLine(chatId, userId, text) flatMap {
         _ ?? { line =>
-          pushLine(chatId, line) >>- {
-            if (publicSource.isDefined) cached invalidate chatId
-            shutup ! {
-              publicSource match {
-                case Some(source) => RecordPublicChat(userId, text, source)
-                case _            => RecordPrivateChat(chatId.value, userId, text)
+          linkCheck(line, publicSource) flatMap {
+            case false =>
+              logger.info(s"Link check rejected $line in $publicSource")
+              funit
+            case true =>
+              pushLine(chatId, line) >>- {
+                if (publicSource.isDefined) cached invalidate chatId
+                shutup ! {
+                  publicSource match {
+                    case Some(source) => RecordPublicChat(userId, text, source)
+                    case _            => RecordPrivateChat(chatId.value, userId, text)
+                  }
+                }
+                publish(chatId, actorApi.ChatLine(chatId, line), busChan)
+                lila.mon.chat.message(publicSource.fold("player")(_.parentName), line.troll).increment()
               }
-            }
-            publish(chatId, actorApi.ChatLine(chatId, line), busChan)
-            lila.mon.chat.message(publicSource.fold("player")(_.parentName), line.troll).increment()
           }
         }
       }
 
+    private def linkCheck(line: UserLine, source: Option[PublicSource]) =
+      source.fold(fuccess(true)) { s =>
+        Bus.ask[Boolean]("chatLinkCheck") { GetLinkCheck(line, s, _) }
+      }
+
     def clear(chatId: Chat.Id) = coll.delete.one($id(chatId)).void
 
     def system(chatId: Chat.Id, text: String, busChan: BusChan.Select): Funit = {
diff --git a/modules/chat/src/main/model.scala b/modules/chat/src/main/model.scala
index 8d79db4451..7efbd622a9 100644
--- a/modules/chat/src/main/model.scala
+++ b/modules/chat/src/main/model.scala
@@ -1,6 +1,8 @@
 package lila.chat
 
 import lila.user.User
+import scala.concurrent.Promise
+import lila.hub.actorApi.shutup.PublicSource
 
 case class UserModInfo(
     user: User,
@@ -21,3 +23,5 @@ object BusChan {
 
   type Select = BusChan.type => BusChan
 }
+
+case class GetLinkCheck(line: UserLine, source: PublicSource, promise: Promise[Boolean])
diff --git a/modules/common/src/main/HTTPRequest.scala b/modules/common/src/main/HTTPRequest.scala
index 45a08e7993..2d9f0c6fda 100644
--- a/modules/common/src/main/HTTPRequest.scala
+++ b/modules/common/src/main/HTTPRequest.scala
@@ -67,7 +67,7 @@ object HTTPRequest {
   case class UaMatcher(rStr: String) {
     private val regex = rStr.r
 
-    def apply(req: RequestHeader): Boolean = userAgent(req) ?? { regex.find(_) }
+    def apply(req: RequestHeader): Boolean = userAgent(req) ?? regex.find
   }
 
   def isFishnet(req: RequestHeader) = req.path startsWith "/fishnet/"
diff --git a/modules/security/src/main/Promotion.scala b/modules/security/src/main/Promotion.scala
index b5df6925a2..7d37236759 100644
--- a/modules/security/src/main/Promotion.scala
+++ b/modules/security/src/main/Promotion.scala
@@ -9,7 +9,7 @@ import lila.common.config.NetDomain
 final class PromotionApi(domain: NetDomain) {
 
   def test(user: User)(text: String): Boolean =
-    user.isVerified || {
+    user.isVerified || user.isAdmin || {
       val promotions = extract(text)
       promotions.isEmpty || {
         val prev   = ~cache.getIfPresent(user.id)
@@ -35,6 +35,8 @@ final class PromotionApi(domain: NetDomain) {
     s"$domain/team/([\\w-]+)",
     s"$domain/tournament/(\\w+)",
     s"$domain/swiss/(\\w+)",
+    s"$domain/simul/(\\w+)",
+    s"$domain/study/(\\w+)",
     """(?:youtube\.com|youtu\.be)/(?:watch)?(?:\?v=)?([^"&?/ ]{11})""",
     """youtube\.com/channel/([\w-]{24})""",
     """twitch\.tv/([a-zA-Z0-9](?:\w{2,24}+))"""
diff --git a/modules/simul/src/main/Simul.scala b/modules/simul/src/main/Simul.scala
index 0a59890202..83f81824b7 100644
--- a/modules/simul/src/main/Simul.scala
+++ b/modules/simul/src/main/Simul.scala
@@ -17,7 +17,7 @@ case class Simul(
     variants: List[Variant],
     position: Option[StartingPosition],
     createdAt: DateTime,
-    hostId: String,
+    hostId: User.ID,
     hostRating: Int,
     hostGameId: Option[String], // game the host is focusing on
     startedAt: Option[DateTime],
diff --git a/modules/simul/src/main/SimulApi.scala b/modules/simul/src/main/SimulApi.scala
index 4e0a94d669..df87014d72 100644
--- a/modules/simul/src/main/SimulApi.scala
+++ b/modules/simul/src/main/SimulApi.scala
@@ -6,8 +6,10 @@ import play.api.libs.json.Json
 import scala.concurrent.duration._
 
 import lila.common.{ Bus, Debouncer }
+import lila.db.dsl._
 import lila.game.{ Game, GameRepo, PerfPicker }
 import lila.hub.actorApi.timeline.{ Propagate, SimulCreate, SimulJoin }
+import lila.hub.LightTeam.TeamID
 import lila.memo.CacheApi._
 import lila.socket.Socket.SendToFlag
 import lila.user.{ User, UserRepo }
@@ -222,6 +224,9 @@ final class SimulApi(
   def idToName(id: Simul.ID): Fu[Option[String]] =
     repo find id dmap2 { _.fullName }
 
+  def teamOf(id: Simul.ID): Fu[Option[TeamID]] =
+    repo.coll.primitiveOne[TeamID]($id(id), "team")
+
   private def makeGame(simul: Simul, host: User)(
       pairingAndNumber: (SimulPairing, Int)
   ): Fu[(Game, chess.Color)] =
diff --git a/modules/simul/src/main/SimulRepo.scala b/modules/simul/src/main/SimulRepo.scala
index b0954dca58..a1811822be 100644
--- a/modules/simul/src/main/SimulRepo.scala
+++ b/modules/simul/src/main/SimulRepo.scala
@@ -10,7 +10,7 @@ import lila.db.BSON.BSONJodaDateTimeHandler
 import lila.db.dsl._
 import lila.user.User
 
-final private[simul] class SimulRepo(simulColl: Coll)(implicit ec: scala.concurrent.ExecutionContext) {
+final private[simul] class SimulRepo(val coll: Coll)(implicit ec: scala.concurrent.ExecutionContext) {
 
   implicit private val SimulStatusBSONHandler = tryHandler[SimulStatus](
     { case BSONInteger(v) => SimulStatus(v) toTry s"No such simul status: $v" },
@@ -57,13 +57,13 @@ final private[simul] class SimulRepo(simulColl: Coll)(implicit ec: scala.concurr
   private val createdSort    = $sort desc "createdAt"
 
   def find(id: Simul.ID): Fu[Option[Simul]] =
-    simulColl.byId[Simul](id)
+    coll.byId[Simul](id)
 
   def byIds(ids: List[Simul.ID]): Fu[List[Simul]] =
-    simulColl.byIds[Simul](ids)
+    coll.byIds[Simul](ids)
 
   def exists(id: Simul.ID): Fu[Boolean] =
-    simulColl.exists($id(id))
+    coll.exists($id(id))
 
   def findStarted(id: Simul.ID): Fu[Option[Simul]] =
     find(id) map (_ filter (_.isStarted))
@@ -72,22 +72,22 @@ final private[simul] class SimulRepo(simulColl: Coll)(implicit ec: scala.concurr
     find(id) map (_ filter (_.isCreated))
 
   def findPending(hostId: User.ID): Fu[List[Simul]] =
-    simulColl.list[Simul](createdSelect ++ $doc("hostId" -> hostId))
+    coll.list[Simul](createdSelect ++ $doc("hostId" -> hostId))
 
   def byTeamLeaders(teamId: String, hostIds: Seq[User.ID]): Fu[List[Simul]] =
-    simulColl
+    coll
       .find(
         createdSelect ++
           $doc("hostId" $in hostIds, "team" $in List(BSONString(teamId)))
       )
-      .hint(simulColl hint $doc("hostId" -> 1))
+      .hint(coll hint $doc("hostId" -> 1))
       .cursor[Simul]()
       .list()
 
   private val featurableSelect = $doc("featurable" -> true)
 
   def allCreatedFeaturable: Fu[List[Simul]] =
-    simulColl
+    coll
       .find(
         // hits partial index hostSeenAt_-1
         createdSelect ++ featurableSelect ++ $doc(
@@ -96,7 +96,7 @@ final private[simul] class SimulRepo(simulColl: Coll)(implicit ec: scala.concurr
         )
       )
       .sort(createdSort)
-      .hint(simulColl hint $doc("hostSeenAt" -> -1))
+      .hint(coll hint $doc("hostSeenAt" -> -1))
       .cursor[Simul]()
       .list() map {
       _.foldLeft(List.empty[Simul]) {
@@ -106,29 +106,29 @@ final private[simul] class SimulRepo(simulColl: Coll)(implicit ec: scala.concurr
     }
 
   def allStarted: Fu[List[Simul]] =
-    simulColl
+    coll
       .find(startedSelect)
       .sort(createdSort)
       .cursor[Simul]()
       .list()
 
   def allFinishedFeaturable(max: Int): Fu[List[Simul]] =
-    simulColl
+    coll
       .find(finishedSelect ++ featurableSelect)
       .sort($sort desc "finishedAt")
       .cursor[Simul]()
       .list(max)
 
   def allNotFinished =
-    simulColl.list[Simul]($doc("status" $ne SimulStatus.Finished.id))
+    coll.list[Simul]($doc("status" $ne SimulStatus.Finished.id))
 
   def create(simul: Simul, featurable: Boolean): Funit =
-    simulColl.insert one {
+    coll.insert one {
       SimulBSONHandler.writeTry(simul).get ++ featurable.??(featurableSelect)
     } void
 
   def update(simul: Simul, featurable: Option[Boolean]) =
-    simulColl.update
+    coll.update
       .one(
         $id(simul.id),
         $set(SimulBSONHandler writeTry simul get) ++ featurable.?? { feat =>
@@ -138,10 +138,10 @@ final private[simul] class SimulRepo(simulColl: Coll)(implicit ec: scala.concurr
       .void
 
   def remove(simul: Simul) =
-    simulColl.delete.one($id(simul.id)).void
+    coll.delete.one($id(simul.id)).void
 
   def setHostGameId(simul: Simul, gameId: String) =
-    simulColl.update
+    coll.update
       .one(
         $id(simul.id),
         $set("hostGameId" -> gameId)
@@ -149,7 +149,7 @@ final private[simul] class SimulRepo(simulColl: Coll)(implicit ec: scala.concurr
       .void
 
   def setHostSeenNow(simul: Simul) =
-    simulColl.update
+    coll.update
       .one(
         $id(simul.id),
         $set("hostSeenAt" -> DateTime.now)
@@ -157,7 +157,7 @@ final private[simul] class SimulRepo(simulColl: Coll)(implicit ec: scala.concurr
       .void
 
   def setText(simul: Simul, text: String) =
-    simulColl.update
+    coll.update
       .one(
         $id(simul.id),
         $set("text" -> text)
@@ -165,7 +165,7 @@ final private[simul] class SimulRepo(simulColl: Coll)(implicit ec: scala.concurr
       .void
 
   def cleanup =
-    simulColl.delete.one(
+    coll.delete.one(
       createdSelect ++ $doc(
         "createdAt" -> $doc("$lt" -> (DateTime.now minusMinutes 60))
       )
diff --git a/modules/study/src/main/StudyMember.scala b/modules/study/src/main/StudyMember.scala
index 64e9fe62a9..af92aa7b7a 100644
--- a/modules/study/src/main/StudyMember.scala
+++ b/modules/study/src/main/StudyMember.scala
@@ -32,7 +32,8 @@ case class StudyMembers(members: StudyMember.MemberMap) {
 
   def get = members.get _
 
-  def ids = members.keys
+  def ids   = members.keys
+  def idSet = members.keySet
 
   def contributorIds: Set[User.ID] =
     members.view.collect {
diff --git a/modules/swiss/src/main/SwissApi.scala b/modules/swiss/src/main/SwissApi.scala
index 147c0a8ced..ed9324492d 100644
--- a/modules/swiss/src/main/SwissApi.scala
+++ b/modules/swiss/src/main/SwissApi.scala
@@ -452,6 +452,9 @@ final class SwissApi(
       .sort($sort desc "startsAt")
       .cursor[Swiss]()
 
+  def teamOf(id: Swiss.Id): Fu[Option[TeamID]] =
+    colls.swiss.primitiveOne[TeamID]($id(id), "teamId")
+
   private def recomputeAndUpdateAll(id: Swiss.Id): Funit =
     scoring(id).flatMap {
       _ ?? { res =>
diff --git a/modules/team/src/main/TeamApi.scala b/modules/team/src/main/TeamApi.scala
index f5c8388152..e69d6d4cfe 100644
--- a/modules/team/src/main/TeamApi.scala
+++ b/modules/team/src/main/TeamApi.scala
@@ -30,7 +30,7 @@ final class TeamApi(
 
   import BSONHandlers._
 
-  def team(id: Team.ID) = teamRepo.coll.byId[Team](id)
+  def team(id: Team.ID) = teamRepo byId id
 
   def leaderTeam(id: Team.ID) = teamRepo.coll.byId[LeaderTeam](id, $doc("name" -> true))
 
diff --git a/modules/team/src/main/TeamRepo.scala b/modules/team/src/main/TeamRepo.scala
index c831f7da47..269b85d172 100644
--- a/modules/team/src/main/TeamRepo.scala
+++ b/modules/team/src/main/TeamRepo.scala
@@ -15,6 +15,8 @@ final class TeamRepo(val coll: Coll)(implicit ec: scala.concurrent.ExecutionCont
 
   private val lightProjection = $doc("name" -> true).some
 
+  def byId(id: Team.ID) = coll.byId[Team](id)
+
   def byOrderedIds(ids: Seq[Team.ID]) = coll.byOrderedIds[Team, Team.ID](ids)(_.id)
 
   def byLeader(id: Team.ID, leaderId: User.ID): Fu[Option[Team]] =
diff --git a/modules/tournament/src/main/TournamentRepo.scala b/modules/tournament/src/main/TournamentRepo.scala
index 72610f7d74..2f7454f21b 100644
--- a/modules/tournament/src/main/TournamentRepo.scala
+++ b/modules/tournament/src/main/TournamentRepo.scala
@@ -144,6 +144,9 @@ final class TournamentRepo(val coll: Coll, playerCollName: CollName)(implicit
   private[tournament] def setForTeam(tourId: Tournament.ID, teamId: TeamID) =
     coll.update.one($id(tourId), $addToSet("forTeams" -> teamId))
 
+  def isForTeam(tourId: Tournament.ID, teamId: TeamID) =
+    coll.exists($id(tourId) ++ $doc("forTeams" -> teamId))
+
   private[tournament] def withdrawableIds(
       userId: User.ID,
       teamId: Option[TeamID] = None
diff --git a/modules/user/src/main/User.scala b/modules/user/src/main/User.scala
index e73e0d11c9..96f50d2fe2 100644
--- a/modules/user/src/main/User.scala
+++ b/modules/user/src/main/User.scala
@@ -119,8 +119,10 @@ case class User(
 
   def addRole(role: String) = copy(roles = role :: roles)
 
-  def isVerified = roles.exists(_ contains "ROLE_VERIFIED")
-  def isApiHog   = roles.exists(_ contains "ROLE_API_HOG")
+  def isVerified   = roles.exists(_ contains "ROLE_VERIFIED")
+  def isSuperAdmin = roles.exists(_ contains "ROLE_SUPER_ADMIN")
+  def isAdmin      = roles.exists(_ contains "ROLE_ADMIN") || isSuperAdmin
+  def isApiHog     = roles.exists(_ contains "ROLE_API_HOG")
 }
 
 object User {