diff --git a/pluto-kotlin-client-sdk/build.gradle b/pluto-kotlin-client-sdk/build.gradle
index 3cdd7cd..9106f40 100644
--- a/pluto-kotlin-client-sdk/build.gradle
+++ b/pluto-kotlin-client-sdk/build.gradle
@@ -4,7 +4,7 @@ apply plugin: 'kotlin-android-extensions'
 apply plugin: 'maven-publish'
 
 buildscript {
-    ext.versionCode = 11
+    ext.versionCode = 12
     ext.versionName = '0.5'
 }
 
@@ -28,7 +28,6 @@ android {
             proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
         }
     }
-
 }
 
 task sourceJar(type: Jar) {
diff --git a/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/Pluto+Binding.kt b/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/Pluto+Binding.kt
new file mode 100644
index 0000000..af88e3d
--- /dev/null
+++ b/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/Pluto+Binding.kt
@@ -0,0 +1,111 @@
+package com.mushare.plutosdk
+
+import retrofit2.Call
+import retrofit2.Callback
+import retrofit2.Response
+
+val availableLoginTypes: Array<Pluto.LoginType>
+    get() = arrayOf(Pluto.LoginType.mail, Pluto.LoginType.mail)
+
+val Pluto.availableBindings: Array<PlutoUserBinding>?
+    get() = data.user?.bindings
+
+fun Pluto.bind(
+    type: Pluto.LoginType,
+    authString: String,
+    success: () -> Unit,
+    error: ((PlutoError) -> Unit)? = null,
+    handler: Pluto.PlutoRequestHandler? = null
+) {
+    getAuthorizationHeader(
+        completion = { header ->
+            if (header == null) {
+                handler?.setCall(null)
+                error?.invoke(PlutoError.notSignIn)
+                return@getAuthorizationHeader
+            }
+
+            val postData = when (type) {
+                Pluto.LoginType.mail -> {
+                    BindPostData(
+                        type = type.identifier,
+                        mail = authString
+                    )
+                }
+                Pluto.LoginType.google -> {
+                    BindPostData(
+                        type = type.identifier,
+                        idToken = authString
+                    )
+                }
+            }
+            plutoService.bind(postData, header).apply {
+                enqueue(object : Callback<PlutoResponse> {
+                    override fun onFailure(call: Call<PlutoResponse>, t: Throwable) {
+                        t.printStackTrace()
+                        error?.invoke(PlutoError.badRequest)
+                    }
+
+                    override fun onResponse(
+                        call: Call<PlutoResponse>,
+                        response: Response<PlutoResponse>
+                    ) {
+                        val plutoResponse = response.body()
+                        if (plutoResponse != null) {
+                            if (plutoResponse.statusOK()) {
+                                success()
+                            } else {
+                                error?.invoke(plutoResponse.errorCode())
+                            }
+                        } else {
+                            error?.invoke(parseErrorCodeFromErrorBody(response.errorBody(), gson))
+                        }
+                    }
+                })
+            }
+        }
+    )
+}
+
+fun Pluto.unbind(
+    type: Pluto.LoginType,
+    success: () -> Unit,
+    error: ((PlutoError) -> Unit)? = null,
+    handler: Pluto.PlutoRequestHandler? = null
+) {
+    getAuthorizationHeader(
+        completion = { header ->
+            if (header == null) {
+                handler?.setCall(null)
+                error?.invoke(PlutoError.notSignIn)
+                return@getAuthorizationHeader
+            }
+
+            val postData = UnbindPostData(type.identifier)
+            plutoService.unbind(postData, header).apply {
+                enqueue(object : Callback<PlutoResponse> {
+                    override fun onFailure(call: Call<PlutoResponse>, t: Throwable) {
+                        t.printStackTrace()
+                        error?.invoke(PlutoError.badRequest)
+                    }
+
+                    override fun onResponse(
+                        call: Call<PlutoResponse>,
+                        response: Response<PlutoResponse>
+                    ) {
+                        val plutoResponse = response.body()
+                        if (plutoResponse != null) {
+                            if (plutoResponse.statusOK()) {
+                                success()
+                            } else {
+                                error?.invoke(plutoResponse.errorCode())
+                            }
+                        } else {
+                            error?.invoke(parseErrorCodeFromErrorBody(response.errorBody(), gson))
+                        }
+                    }
+                })
+            }
+        }
+    )
+}
\ No newline at end of file
diff --git a/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/Pluto.kt b/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/Pluto.kt
index 23a92d8..bcecb1f 100644
--- a/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/Pluto.kt
+++ b/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/Pluto.kt
@@ -30,6 +30,20 @@ class Pluto private constructor() {
         }
     }
 
+    enum class LoginType(val identifier: String) {
+        mail("mail"),
+        google("google");
+        // TODO: wechat
+
+        companion object {
+            private val map = values().associateBy(LoginType::identifier)
+
+            fun from(identifier: String): LoginType? {
+                return map.getValue(identifier)
+            }
+        }
+    }
+
     internal val data by lazy { PlutoModel(context) }
 
     val state: MutableLiveData<State> by lazy {
diff --git a/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/PlutoModel.kt b/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/PlutoModel.kt
index e439e5b..cb1107d 100644
--- a/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/PlutoModel.kt
+++ b/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/PlutoModel.kt
@@ -108,5 +108,11 @@ data class PlutoUser(
     @field:SerializedName("user_id") var userId: String,
     @field:SerializedName("user_id_updated") var userIdUpdated: Boolean,
     @field:SerializedName("avatar") var avatar: String,
-    @field:SerializedName("name") var name: String
+    @field:SerializedName("name") var name: String,
+    @field:SerializedName("bindings") var bindings: Array<PlutoUserBinding>
+)
+
+data class PlutoUserBinding(
+    @field:SerializedName("login_type") val loginType: Pluto.LoginType,
+    @field:SerializedName("mail") var mail: String?
 )
\ No newline at end of file
diff --git a/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/PlutoService.kt b/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/PlutoService.kt
index 7225bb1..0000f7b 100644
--- a/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/PlutoService.kt
+++ b/pluto-kotlin-client-sdk/src/main/java/com/mushare/plutosdk/PlutoService.kt
@@ -48,6 +48,18 @@ interface PlutoService {
         @Body body: UpdateUserInfoPutData,
         @HeaderMap authorizationHeader: Map<String, String>
     ): Call<PlutoResponse>
+
+    @POST("v1/user/binding")
+    fun bind(
+        @Body body: BindPostData,
+        @HeaderMap authorizationHeader: Map<String, String>
+    ): Call<PlutoResponse>
+
+    @POST("/v1/user/unbinding")
+    fun unbind(
+        @Body body: UnbindPostData,
+        @HeaderMap authorizationHeader: Map<String, String>
+    ): Call<PlutoResponse>
 }
 
 class RefreshAuthPostData(
@@ -91,4 +103,15 @@ class UpdateUserInfoPutData(
     @field:SerializedName("name") var name: String?,
     @field:SerializedName("avatar") var avatar: String?,
     @field:SerializedName("user_id") var userId: String?
+)
+
+class BindPostData(
+    @field:SerializedName("type") var type: String,
+    @field:SerializedName("code") var code: String? = null,
+    @field:SerializedName("id_token") var idToken: String? = null,
+    @field:SerializedName("mail") var mail: String? = null
+)
+
+class UnbindPostData(
+    @field:SerializedName("type") var type: String
 )
\ No newline at end of file