diff --git a/doc/api.oa3 b/doc/api.oa3
index c531218b..4da3e0c6 100644
--- a/doc/api.oa3
+++ b/doc/api.oa3
@@ -2045,12 +2045,12 @@ paths:
           application/json:
             schema:
               $ref: '#/components/schemas/Subject'
-                  
+           
   /content/channels/{channelId}/groups/{groupId}:
     put:
       tags:
         - content
-      description: Set group for channels. Access granted to app tokens for account holder. 
+      description: Set group for read access to channel. Access granted to app tokens for account holder. 
       operationId: set-channel-group
       security:
         - bearerAuth: []
@@ -2085,7 +2085,7 @@ paths:
     delete:
       tags:
         - content
-      description: Clear sharing group for channel. Access granted to app tokens for account holder.
+      description: Clear read access to channel for group. Access granted to app tokens for account holder.
       operationId: clear-channel-group
       security:
         - bearerAuth: []
@@ -2118,6 +2118,78 @@ paths:
         '500':
           description: internal server error
           
+  /content/channels/{channelId}/cards/{cardId}:
+    put:
+      tags:
+        - content
+      description: Set card for write access to channel. Access granted to app tokens for account holder. 
+      operationId: set-channel-card
+      security:
+        - bearerAuth: []
+      parameters:
+        - name: channelId
+          in: path
+          description: specified channel id 
+          required: true
+          schema:
+            type: string
+        - name: cardId
+          in: path
+          description: specified card id 
+          required: true
+          schema:
+            type: string
+      responses:
+        '200':
+          description: success
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Channel'
+        '401':
+          description: permission denied
+        '404':
+          description: card or group not found
+        '410':
+          description: account disabled
+        '500':
+          description: internal server error
+    delete:
+      tags:
+        - content
+      description: Clear write access to channel for card. Access granted to app tokens for account holder.
+      operationId: clear-channel-card
+      security:
+        - bearerAuth: []
+      parameters:
+        - name: channelId
+          in: path
+          description: specified channel id 
+          required: true
+          schema:
+            type: string
+        - name: cardId
+          in: path
+          description: specified card id 
+          required: true
+          schema:
+            type: string
+      responses:
+        '200':
+          description: success
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Channel'
+        '401':
+          description: permission denied
+        '404':
+          description: card or group not found
+        '410':
+          description: account disabled
+        '500':
+          description: internal server error
+          
   /content/channels/{channelId}/topics:
     get:
       tags:
@@ -3141,18 +3213,12 @@ components:
         updated:
           type: integer
           format: int64
-        viewers:
+        groups:
+          $ref: '#/components/schemas/ChannelGroups'
+        cards:
           type: array
           items:
             type: string
-        viewerGroups:
-          $ref: '#/components/schemas/ChannelGroups'
-        members:
-          type: array
-          items:
-            type: string
-        memberGroups:
-          $ref: '#/components/schemas/ChannelGroups'
           
     ChannelSize:
       type: object
@@ -3520,3 +3586,4 @@ components:
       scheme: bearer
 
 
+
diff --git a/net/server/internal/api_clearCardGroup.go b/net/server/internal/api_clearCardGroup.go
new file mode 100644
index 00000000..e83fd870
--- /dev/null
+++ b/net/server/internal/api_clearCardGroup.go
@@ -0,0 +1,84 @@
+package databag
+
+import (
+  "errors"
+  "net/http"
+  "gorm.io/gorm"
+  "github.com/gorilla/mux"
+  "databag/internal/store"
+)
+
+func ClearCardGroup(w http.ResponseWriter, r *http.Request) {
+
+  account, code, err := BearerAppToken(r, false);
+  if err != nil {
+    ErrResponse(w, code, err)
+    return
+  }
+
+  // scan parameters
+  params := mux.Vars(r)
+  cardId := params["cardId"]
+  groupId := params["groupId"]
+
+  // load referenced card
+  var cardSlot store.CardSlot
+  if err := store.DB.Preload("Card").Where("account_id = ? AND card_slot_id = ?", account.ID, cardId).First(&cardSlot).Error; err != nil {
+    if errors.Is(err, gorm.ErrRecordNotFound) {
+      ErrResponse(w, http.StatusNotFound, err)
+    } else {
+      ErrResponse(w, http.StatusInternalServerError, err)
+    }
+    return
+  }
+  if cardSlot.Card == nil {
+    ErrResponse(w, http.StatusNotFound, errors.New("card has been deleted"))
+    return
+  }
+
+  // load referenced group
+  var groupSlot store.GroupSlot
+  if err := store.DB.Preload("Group").Where("account_id = ? AND group_slot_id = ?", account.ID, groupId).First(&groupSlot).Error; err != nil {
+    if !errors.Is(err, gorm.ErrRecordNotFound) {
+      ErrResponse(w, http.StatusInternalServerError, err)
+    } else {
+      ErrResponse(w, http.StatusNotFound, err)
+    }
+    return
+  }
+  if groupSlot.Group == nil {
+    ErrResponse(w, http.StatusNotFound, errors.New("referenced deleted group"))
+    return
+  }
+
+  // save and update revision
+  cardSlot.Revision = account.CardRevision + 1
+  err = store.DB.Transaction(func(tx *gorm.DB) error {
+    if res := tx.Model(&cardSlot.Card).Association("Groups").Delete(groupSlot.Group); res != nil {
+      return res
+    }
+    if res := tx.Model(&cardSlot.Card).Update("detail_revision", cardSlot.Card.DetailRevision + 1).Error; res != nil {
+      return res
+    }
+    if res := tx.Model(&cardSlot.Card).Update("view_revision", cardSlot.Card.ViewRevision + 1).Error; res != nil {
+      return res
+    }
+    if res := tx.Model(&cardSlot).Update("revision", account.CardRevision + 1).Error; res != nil {
+      return res
+    }
+    if res := tx.Model(&account).Update("card_revision", account.CardRevision + 1).Error; res != nil {
+      return res
+    }
+    return nil
+  })
+  if err != nil {
+    ErrResponse(w, http.StatusInternalServerError, err)
+    return
+  }
+
+  SetContactViewNotification(account, cardSlot.Card)
+  SetStatus(account)
+  WriteResponse(w, getCardModel(&cardSlot))
+}
+
+
diff --git a/net/server/internal/api_contact.go b/net/server/internal/api_contact.go
index 06708f96..841ed0b2 100644
--- a/net/server/internal/api_contact.go
+++ b/net/server/internal/api_contact.go
@@ -13,11 +13,6 @@ import (
 	"net/http"
 )
 
-func ClearCardGroup(w http.ResponseWriter, r *http.Request) {
-	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
-	w.WriteHeader(http.StatusOK)
-}
-
 func GetCloseMessage(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
 	w.WriteHeader(http.StatusOK)
diff --git a/net/server/internal/api_content.go b/net/server/internal/api_content.go
index 2c6e66f1..4babd62b 100644
--- a/net/server/internal/api_content.go
+++ b/net/server/internal/api_content.go
@@ -33,6 +33,11 @@ func AddChannelTopicTag(w http.ResponseWriter, r *http.Request) {
 	w.WriteHeader(http.StatusOK)
 }
 
+func ClearChannelCard(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
+	w.WriteHeader(http.StatusOK)
+}
+
 func ClearChannelGroup(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
 	w.WriteHeader(http.StatusOK)
@@ -118,6 +123,11 @@ func RemoveChannelTopicTag(w http.ResponseWriter, r *http.Request) {
 	w.WriteHeader(http.StatusOK)
 }
 
+func SetChannelCard(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
+	w.WriteHeader(http.StatusOK)
+}
+
 func SetChannelConfirmed(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
 	w.WriteHeader(http.StatusOK)
diff --git a/net/server/internal/api_getCard.go b/net/server/internal/api_getCard.go
index 2a122b23..1945b34a 100644
--- a/net/server/internal/api_getCard.go
+++ b/net/server/internal/api_getCard.go
@@ -18,7 +18,7 @@ func GetCard(w http.ResponseWriter, r *http.Request) {
   cardId := mux.Vars(r)["cardId"]
 
   var slot store.CardSlot
-  if err := store.DB.Preload("Card.Groups").Where("account_id = ? AND card_slot_id = ?", account.ID, cardId).First(&slot).Error; err != nil {
+  if err := store.DB.Preload("Card.Groups.GroupSlot").Where("account_id = ? AND card_slot_id = ?", account.ID, cardId).First(&slot).Error; err != nil {
     if errors.Is(err, gorm.ErrRecordNotFound) {
       ErrResponse(w, http.StatusNotFound, err)
     } else {
diff --git a/net/server/internal/api_setArticleRevision.go b/net/server/internal/api_setArticleRevision.go
index 8a38ad9d..dbff352b 100644
--- a/net/server/internal/api_setArticleRevision.go
+++ b/net/server/internal/api_setArticleRevision.go
@@ -32,7 +32,7 @@ func NotifyArticleRevision(card *store.Card, revision int64) error {
 
   act := &card.Account
   err := store.DB.Transaction(func(tx *gorm.DB) error {
-    if res := tx.Model(card).Where("id = ?", card.ID).Update("notified_profile", revision).Error; res != nil {
+    if res := tx.Model(card).Where("id = ?", card.ID).Update("notified_article", revision).Error; res != nil {
       return res
     }
     if res := tx.Model(&card.CardSlot).Where("id = ?", card.CardSlot.ID).Update("revision", act.CardRevision+1).Error; res != nil {
diff --git a/net/server/internal/api_setCardGroup.go b/net/server/internal/api_setCardGroup.go
index e8055f10..2e61d68a 100644
--- a/net/server/internal/api_setCardGroup.go
+++ b/net/server/internal/api_setCardGroup.go
@@ -51,19 +51,22 @@ func SetCardGroup(w http.ResponseWriter, r *http.Request) {
   }
 
   // save and update revision
-  slot.Card.Groups = append(slot.Card.Groups, *groupSlot.Group)
-  slot.Card.ViewRevision += 1
-  slot.Revision = account.CardRevision + 1
   err = store.DB.Transaction(func(tx *gorm.DB) error {
+    if res := tx.Model(&slot.Card).Association("Groups").Append(groupSlot.Group); res != nil {
+      return res
+    }
+    if res := tx.Model(&slot.Card).Update("detail_revision", slot.Card.DetailRevision + 1).Error; res != nil {
+      return res
+    }
+    if res := tx.Model(&slot.Card).Update("view_revision", slot.Card.ViewRevision + 1).Error; res != nil {
+      return res
+    }
+    if res := tx.Model(&slot).Update("revision", account.CardRevision + 1).Error; res != nil {
+      return res
+    }
     if res := tx.Model(&account).Update("card_revision", account.CardRevision + 1).Error; res != nil {
       return res
     }
-    if res := tx.Save(&slot.Card).Error; res != nil {
-      return res
-    }
-    if res := tx.Preload("CardData.Groups").Save(&slot).Error; res != nil {
-      return res
-    }
     return nil
   })
   if err != nil {
diff --git a/net/server/internal/api_setChannelRevision.go b/net/server/internal/api_setChannelRevision.go
index c4ed953f..1fd9ca93 100644
--- a/net/server/internal/api_setChannelRevision.go
+++ b/net/server/internal/api_setChannelRevision.go
@@ -32,7 +32,7 @@ func NotifyChannelRevision(card *store.Card, revision int64) error {
 
   act := &card.Account
   err := store.DB.Transaction(func(tx *gorm.DB) error {
-    if res := tx.Model(card).Where("id = ?", card.ID).Update("notified_profile", revision).Error; res != nil {
+    if res := tx.Model(card).Where("id = ?", card.ID).Update("notified_channel", revision).Error; res != nil {
       return res
     }
     if res := tx.Model(&card.CardSlot).Where("id = ?", card.CardSlot.ID).Update("revision", act.CardRevision+1).Error; res != nil {
diff --git a/net/server/internal/api_setViewRevision.go b/net/server/internal/api_setViewRevision.go
index 0b0f4765..d6791729 100644
--- a/net/server/internal/api_setViewRevision.go
+++ b/net/server/internal/api_setViewRevision.go
@@ -32,7 +32,7 @@ func NotifyViewRevision(card *store.Card, revision int64) error {
 
   act := &card.Account
   err := store.DB.Transaction(func(tx *gorm.DB) error {
-    if res := tx.Model(card).Where("id = ?", card.ID).Update("notified_profile", revision).Error; res != nil {
+    if res := tx.Model(card).Where("id = ?", card.ID).Update("notified_view", revision).Error; res != nil {
       return res
     }
     if res := tx.Model(&card.CardSlot).Where("id = ?", card.CardSlot.ID).Update("revision", act.CardRevision+1).Error; res != nil {
diff --git a/net/server/internal/models.go b/net/server/internal/models.go
index f4141222..8ec9c11d 100644
--- a/net/server/internal/models.go
+++ b/net/server/internal/models.go
@@ -177,13 +177,9 @@ type ChannelDetail struct {
 
 	Updated int64 `json:"updated"`
 
-	Viewers []string `json:"viewers,omitempty"`
+	Groups *ChannelGroups `json:"groups,omitempty"`
 
-	ViewerGroups *ChannelGroups `json:"viewerGroups,omitempty"`
-
-	Members []string `json:"members,omitempty"`
-
-	MemberGroups *ChannelGroups `json:"memberGroups,omitempty"`
+	Cards []string `json:"cards"`
 }
 
 type ChannelGroups struct {
diff --git a/net/server/internal/routers.go b/net/server/internal/routers.go
index 970380ff..54d9fee5 100644
--- a/net/server/internal/routers.go
+++ b/net/server/internal/routers.go
@@ -145,13 +145,6 @@ var routes = Routes{
 		GetAccountUsername,
 	},
 
-	Route{
-		"GetCard",
-		strings.ToUpper("Get"),
-		"/contact/cards/{cardId}",
-		GetCard,
-	},
-
 	Route{
 		"GetPublicStatus",
 		strings.ToUpper("Get"),
@@ -523,6 +516,13 @@ var routes = Routes{
 		AddChannelTopicTag,
 	},
 
+	Route{
+		"ClearChannelCard",
+		strings.ToUpper("Delete"),
+		"/content/channels/{channelId}/cards/{cardId}",
+		ClearChannelCard,
+	},
+
 	Route{
 		"ClearChannelGroup",
 		strings.ToUpper("Delete"),
@@ -642,6 +642,13 @@ var routes = Routes{
 		RemoveChannelTopicTag,
 	},
 
+	Route{
+		"SetChannelCard",
+		strings.ToUpper("Put"),
+		"/content/channels/{channelId}/cards/{cardId}",
+		SetChannelCard,
+	},
+
 	Route{
 		"SetChannelConfirmed",
 		strings.ToUpper("Put"),
@@ -719,3 +726,4 @@ var routes = Routes{
 		Status,
 	},
 }
+
diff --git a/net/server/internal/ucContactSync_test.go b/net/server/internal/ucContactSync_test.go
index c0739f69..cf33ea6a 100644
--- a/net/server/internal/ucContactSync_test.go
+++ b/net/server/internal/ucContactSync_test.go
@@ -10,7 +10,7 @@ import (
 func TestContactSync(t *testing.T) {
   var profile Profile
   var msg DataMessage
-  var card Card
+  var card *Card
   param := map[string]string{}
   var img []byte
   var data []byte
@@ -21,6 +21,7 @@ func TestContactSync(t *testing.T) {
   var detailRevision int64
   var detail CardDetail
   var rev *Revision
+  var viewRevision int64
 
   // setup testing group
   set, err := AddTestGroup("contactsync")
@@ -72,7 +73,7 @@ func TestContactSync(t *testing.T) {
 
   // clear card notes
   GetTestRevision(set.B.Revisions)
-  assert.NoError(t, ApiTestMsg(ClearCardNotes, "DELETE", "/conact/cards/{cardId}/notes",
+  assert.NoError(t, ApiTestMsg(ClearCardNotes, "DELETE", "/contact/cards/{cardId}/notes",
     &param, nil, APP_TOKENAPP, set.B.Token, &detail, nil))
   assert.NotEqual(t, rev.Card, GetTestRevision(set.B.Revisions).Card)
   cards = &[]Card{}
@@ -81,4 +82,26 @@ func TestContactSync(t *testing.T) {
   assert.Equal(t, 1, len(*cards))
   assert.NotEqual(t, detailRevision, (*cards)[0].Data.DetailRevision)
 
+  // remove card from group
+  card = &Card{}
+  param["cardId"] = set.B.A.CardId
+  assert.NoError(t, ApiTestMsg(GetCard, "GET", "/contact/cards/{cardId}",
+    &param, nil, APP_TOKENAPP, set.B.Token, card, nil))
+  viewRevision = card.Data.NotifiedView
+
+  card = &Card{}
+  param["cardId"] = set.A.B.CardId
+  param["groupId"] = set.A.B.GroupId
+  assert.NoError(t, ApiTestMsg(ClearCardGroup, "DELETE", "/contact/cards/{cardId}/groups/{groupId}",
+    &param, nil, APP_TOKENAPP, set.A.Token, card, nil))
+  assert.Equal(t, 0, len(card.Data.CardDetail.Groups))
+  assert.NotEqual(t, rev.Card, GetTestRevision(set.B.Revisions).Card)
+
+  card = &Card{}
+  param["cardId"] = set.B.A.CardId
+  assert.NoError(t, ApiTestMsg(GetCard, "GET", "/contact/cards/{cardId}",
+    &param, nil, APP_TOKENAPP, set.B.Token, card, nil))
+  assert.NotEqual(t, viewRevision, card.Data.NotifiedView)
+  PrintMsg(card)
+
 }