diff --git a/clock.go b/clock.go
new file mode 100644
index 00000000..5489cae6
--- /dev/null
+++ b/clock.go
@@ -0,0 +1,59 @@
+package core
+
+import (
+	"sync"
+	"time"
+)
+
+// Clock is a V2Ray feature that returns current time.
+type Clock interface {
+	Feature
+
+	// Now returns current time.
+	Now() time.Time
+}
+
+type syncClock struct {
+	sync.RWMutex
+	Clock
+}
+
+func (c *syncClock) Now() time.Time {
+	c.RLock()
+	defer c.RUnlock()
+
+	if c.Clock == nil {
+		return time.Now()
+	}
+
+	return c.Clock.Now()
+}
+
+func (c *syncClock) Start() error {
+	c.RLock()
+	defer c.RUnlock()
+
+	if c.Clock == nil {
+		return nil
+	}
+
+	return c.Clock.Start()
+}
+
+func (c *syncClock) Close() {
+	c.RLock()
+	defer c.RUnlock()
+
+	if c.Clock == nil {
+		return
+	}
+
+	c.Clock.Close()
+}
+
+func (c *syncClock) Set(clock Clock) {
+	c.Lock()
+	defer c.Unlock()
+
+	c.Clock = clock
+}
diff --git a/v2ray.go b/v2ray.go
index 15275f8c..b6a0de9d 100644
--- a/v2ray.go
+++ b/v2ray.go
@@ -27,6 +27,7 @@ type Instance struct {
 	router        syncRouter
 	ihm           syncInboundHandlerManager
 	ohm           syncOutboundHandlerManager
+	clock         syncClock
 
 	features []Feature
 	id       uuid.UUID
@@ -163,3 +164,8 @@ func (s *Instance) InboundHandlerManager() InboundHandlerManager {
 func (s *Instance) OutboundHandlerManager() OutboundHandlerManager {
 	return &(s.ohm)
 }
+
+// Clock returns the Clock used by this Instance. The returned Clock is always functional.
+func (s *Instance) Clock() Clock {
+	return &(s.clock)
+}