diff --git a/ethwire/client_identity.go b/ethwire/client_identity.go
new file mode 100644
index 000000000..e803406d8
--- /dev/null
+++ b/ethwire/client_identity.go
@@ -0,0 +1,54 @@
+package ethwire
+
+import (
+	"fmt"
+	"runtime"
+)
+
+// should be used in Peer handleHandshake, incorporate Caps, ProtocolVersion, Pubkey etc.
+type ClientIdentity interface {
+	String() string
+}
+
+type SimpleClientIdentity struct {
+	clientString     string
+	clientIdentifier string
+	version          string
+	customIdentifier string
+	os               string
+	implementation   string
+}
+
+func NewSimpleClientIdentity(clientIdentifier string, version string, customIdentifier string) *SimpleClientIdentity {
+	clientIdentity := &SimpleClientIdentity{
+		clientIdentifier: clientIdentifier,
+		version:          version,
+		customIdentifier: customIdentifier,
+		os:               runtime.GOOS,
+		implementation:   "Go",
+	}
+	clientIdentity.init()
+	return clientIdentity
+}
+
+func (c *SimpleClientIdentity) init() {
+	c.clientString = fmt.Sprintf("%s/v%s/%s/%s/%s",
+		c.clientIdentifier,
+		c.version,
+		c.customIdentifier,
+		c.os,
+		c.implementation)
+}
+
+func (c *SimpleClientIdentity) String() string {
+	return c.clientString
+}
+
+func (c *SimpleClientIdentity) SetCustomIdentifier(customIdentifier string) {
+	c.customIdentifier = customIdentifier
+	c.init()
+}
+
+func (c *SimpleClientIdentity) GetCustomIdentifier() string {
+	return c.customIdentifier
+}
diff --git a/ethwire/client_identity_test.go b/ethwire/client_identity_test.go
new file mode 100644
index 000000000..f3c8bfd50
--- /dev/null
+++ b/ethwire/client_identity_test.go
@@ -0,0 +1,30 @@
+package ethwire
+
+import (
+	"fmt"
+	"runtime"
+	"testing"
+)
+
+func TestClientIdentity(t *testing.T) {
+	clientIdentity := NewSimpleClientIdentity("Ethereum(G)", "0.5.16", "test")
+	clientString := clientIdentity.String()
+	expected := fmt.Sprintf("Ethereum(G)/v0.5.16/test/%s/Go", runtime.GOOS)
+	if clientString != expected {
+		t.Error("Expected clientIdentity to be %v, got %v", expected, clientString)
+	}
+	customIdentifier := clientIdentity.GetCustomIdentifier()
+	if customIdentifier != "test" {
+		t.Error("Expected clientIdentity.GetCustomIdentifier() to be 'test', got %v", customIdentifier)
+	}
+	clientIdentity.SetCustomIdentifier("test2")
+	customIdentifier = clientIdentity.GetCustomIdentifier()
+	if customIdentifier != "test2" {
+		t.Error("Expected clientIdentity.GetCustomIdentifier() to be 'test2', got %v", customIdentifier)
+	}
+	clientString = clientIdentity.String()
+	expected = fmt.Sprintf("Ethereum(G)/v0.5.16/test2/%s/Go", runtime.GOOS)
+	if clientString != expected {
+		t.Error("Expected clientIdentity to be %v, got %v", expected, clientString)
+	}
+}