diff --git a/blockbook.go b/blockbook.go
index bc135177..9635ab0e 100644
--- a/blockbook.go
+++ b/blockbook.go
@@ -64,13 +64,15 @@ var (
 )
 
 var (
-	chanSyncIndex       = make(chan struct{})
-	chanSyncMempool     = make(chan struct{})
-	chanSyncIndexDone   = make(chan struct{})
-	chanSyncMempoolDone = make(chan struct{})
-	chain               *bchain.BitcoinRPC
-	mempool             *bchain.Mempool
-	index               *db.RocksDB
+	chanSyncIndex          = make(chan struct{})
+	chanSyncMempool        = make(chan struct{})
+	chanSyncIndexDone      = make(chan struct{})
+	chanSyncMempoolDone    = make(chan struct{})
+	chain                  *bchain.BitcoinRPC
+	mempool                *bchain.Mempool
+	index                  *db.RocksDB
+	callbackOnNewIndexHash []func(hash string)
+	callbackOnNewTxAddr    []func(txid string, addr string)
 )
 
 func main() {
@@ -130,12 +132,9 @@ func main() {
 	}
 
 	if *synchronize {
-		if err := resyncIndex(true); err != nil {
+		if err := resyncIndex(true, nil); err != nil {
 			glog.Fatal("resyncIndex ", err)
 		}
-		go syncIndexLoop()
-		go syncMempoolLoop()
-		chanSyncMempool <- struct{}{}
 	}
 
 	var httpServer *server.HTTPServer
@@ -172,6 +171,15 @@ func main() {
 				}
 			}
 		}()
+		callbackOnNewIndexHash = append(callbackOnNewIndexHash, socketIoServer.OnNewBlockHash)
+	}
+
+	if *synchronize {
+		// start the synchronization loops after the server interfaces are started
+		go syncIndexLoop()
+		go syncMempoolLoop()
+		// sync mempool immediately
+		chanSyncMempool <- struct{}{}
 	}
 
 	var mq *bchain.MQ
@@ -214,7 +222,7 @@ func main() {
 		}
 	}
 
-	if httpServer != nil || mq != nil {
+	if httpServer != nil || socketIoServer != nil || mq != nil {
 		waitForSignalAndShutdown(httpServer, socketIoServer, mq, 5*time.Second)
 	}
 
@@ -254,13 +262,19 @@ func syncIndexLoop() {
 	glog.Info("syncIndexLoop starting")
 	// resync index about every 15 minutes if there are no chanSyncIndex requests, with debounce 1 second
 	tickAndDebounce(resyncIndexPeriodMs*time.Millisecond, debounceResyncIndexMs*time.Millisecond, chanSyncIndex, func() {
-		if err := resyncIndex(false); err != nil {
+		if err := resyncIndex(false, onNewBlockHash); err != nil {
 			glog.Error("syncIndexLoop", err)
 		}
 	})
 	glog.Info("syncIndexLoop stopped")
 }
 
+func onNewBlockHash(hash string) {
+	for _, c := range callbackOnNewIndexHash {
+		c(hash)
+	}
+}
+
 func syncMempoolLoop() {
 	defer close(chanSyncMempoolDone)
 	glog.Info("syncMempoolLoop starting")
@@ -320,7 +334,7 @@ func printResult(txid string, vout uint32, isOutput bool) error {
 	return nil
 }
 
-func resyncIndex(bulk bool) error {
+func resyncIndex(bulk bool, onNewBlock func(hash string)) error {
 	remote, err := chain.GetBestBlockHash()
 	if err != nil {
 		return err
@@ -375,7 +389,7 @@ func resyncIndex(bulk bool) error {
 			if err != nil {
 				return err
 			}
-			return resyncIndex(false)
+			return resyncIndex(false, onNewBlock)
 		}
 	}
 
@@ -420,16 +434,14 @@ func resyncIndex(bulk bool) error {
 			}
 			// after parallel load finish the sync using standard way,
 			// new blocks may have been created in the meantime
-			return resyncIndex(false)
+			return resyncIndex(false, onNewBlock)
 		}
 	}
 
-	return connectBlocks(hash)
+	return connectBlocks(hash, onNewBlock)
 }
 
-func connectBlocks(
-	hash string,
-) error {
+func connectBlocks(hash string, onNewBlock func(hash string)) error {
 	bch := make(chan blockResult, 8)
 	done := make(chan struct{})
 	defer close(done)
@@ -446,6 +458,9 @@ func connectBlocks(
 		if err != nil {
 			return err
 		}
+		if onNewBlock != nil {
+			onNewBlock(res.block.Hash)
+		}
 	}
 
 	if lastRes.block != nil {
diff --git a/server/socketio.go b/server/socketio.go
index 4827bf4a..a71f8961 100644
--- a/server/socketio.go
+++ b/server/socketio.go
@@ -634,7 +634,42 @@ func (s *SocketIoServer) sendTransaction(tx string) (res resultSendTransaction,
 	return
 }
 
+// onSubscribe expects two event subscriptions based on the req parameter (including the doublequotes):
+// "bitcoind/hashblock"
+// "bitcoind/addresstxid",["2MzTmvPJLZaLzD9XdN3jMtQA5NexC3rAPww","2NAZRJKr63tSdcTxTN3WaE9ZNDyXy6PgGuv"]
 func (s *SocketIoServer) onSubscribe(c *gosocketio.Channel, req []byte) interface{} {
-	glog.Info(c.Id(), " onSubscribe ", string(req))
+	r := string(req)
+	glog.Info(c.Id(), " onSubscribe ", r)
+	var sc string
+	i := strings.Index(r, "\",[")
+	if i > 0 {
+		var addrs []string
+		sc = r[1:i]
+		if sc != "bitcoind/addresstxid" {
+			glog.Error(c.Id(), " onSubscribe ", sc, ": invalid data")
+			return nil
+		}
+		err := json.Unmarshal([]byte(r[i+2:]), &addrs)
+		if err != nil {
+			glog.Error(c.Id(), " onSubscribe ", sc, ": ", err)
+			return nil
+		}
+		for _, a := range addrs {
+			c.Join(sc + "-" + a)
+		}
+	} else {
+		sc = r[1 : len(r)-1]
+		if sc != "bitcoind/hashblock" {
+			glog.Error(c.Id(), " onSubscribe ", sc, ": invalid data")
+			return nil
+		}
+		c.Join(sc)
+	}
 	return nil
 }
+
+// OnNewBlockHash notifies users subscribed to bitcoind/hashblock about new block
+func (s *SocketIoServer) OnNewBlockHash(hash string) {
+	glog.Info("broadcasting new block hash ", hash)
+	s.server.BroadcastTo("bitcoind/hashblock", "bitcoind/hashblock", hash)
+}
diff --git a/server/static/test.html b/server/static/test.html
index 02921168..574de0c1 100644
--- a/server/static/test.html
+++ b/server/static/test.html
@@ -188,6 +188,7 @@
             socket.on("bitcoind/hashblock", function (result) {
                 console.log('on bitcoind/hashblock');
                 console.log(result);
+                document.getElementById('subscribeHashBlockResult').innerText += JSON.stringify(result).replace(/,/g, ", ") + "\n";
             });
         }