diff --git a/database.go b/database.go
index 8ee2984..4f7829b 100644
--- a/database.go
+++ b/database.go
@@ -2,7 +2,9 @@ package main
 
 import (
 	"context"
+	"time"
 
+	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
 )
 
@@ -121,3 +123,23 @@ func DbSetGroupById(ctx context.Context, group *Group) error {
 	}
 	return rows.Err()
 }
+
+func DbAddClientsToGroup(ctx context.Context, groupId uint32, clientIds []uint32) error {
+	batch := &pgx.Batch{}
+	now := time.Now()
+	for _, cid := range clientIds {
+		batch.Queue(`
+			INSERT INTO chat_group_members (group_id, user_id, joined_at)
+			VALUES ($1, $2, $3)
+			ON CONFLICT DO NOTHING
+		`, groupId, cid, now)
+	}
+	br := dbConn.SendBatch(ctx, batch)
+	defer br.Close()
+	for range clientIds {
+		if _, err := br.Exec(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
diff --git a/go-socket b/go-socket
index 2704ae6..7af15e3 100755
Binary files a/go-socket and b/go-socket differ
diff --git a/go.mod b/go.mod
index 2902dbf..e6bf2fb 100644
--- a/go.mod
+++ b/go.mod
@@ -8,6 +8,11 @@ require (
 	golang.org/x/crypto v0.49.0
 )
 
+require (
+	github.com/jackc/puddle/v2 v2.2.2 // indirect
+	golang.org/x/sync v0.20.0 // indirect
+)
+
 require (
 	github.com/golang-jwt/jwt/v5 v5.3.1
 	github.com/jackc/pgpassfile v1.0.0 // indirect
diff --git a/http.go b/http.go
index af3ae43..e44f503 100644
--- a/http.go
+++ b/http.go
@@ -202,6 +202,7 @@ func HttpHandleGroupAddClient(response http.ResponseWriter, request *http.Reques
 	ctx := request.Context()
 
 	var group Group
+	group.Id = affectedGroupId
 	groupPtr, err := CacheGetGroup(affectedGroupId)
 	if err == nil {
 		group = *groupPtr
@@ -225,10 +226,28 @@ func HttpHandleGroupAddClient(response http.ResponseWriter, request *http.Reques
 		return
 	}
 
-	usersToAdd := strings.SplitN(usersToAddString, ",", remainingUsersCount+1)
-	if len(usersToAdd) == 0 {
+	userIdStrings := strings.SplitN(usersToAddString, ",", remainingUsersCount+1)
+	if len(userIdStrings) == 0 {
 		http.Error(response, "no users to add", http.StatusBadRequest)
 		return
 	}
 
+	clientIds := make([]uint32, 0, len(userIdStrings))
+	for _, s := range userIdStrings {
+		id, err := ConvertStringUint32(strings.TrimSpace(s))
+		if err != nil {
+			continue
+		}
+		clientIds = append(clientIds, id)
+	}
+	if len(clientIds) == 0 {
+		http.Error(response, "no valid users", http.StatusBadRequest)
+		return
+	}
+
+	err = DbAddClientsToGroup(ctx, group.Id, clientIds)
+	if err != nil {
+		http.Error(response, "internal server error", http.StatusInternalServerError)
+		return
+	}
 }