diff --git a/windows_chat.c b/windows_chat.c
new file mode 100644
index 0000000..3967cfc
--- /dev/null
+++ b/windows_chat.c
@@ -0,0 +1,102 @@
+#include <stdio.h>
+#include <string.h>
+#include <winsock2.h>
+#include <ws2tcpip.h>
+
+#include "common.h"
+
+#pragma comment(lib, "ws2_32.lib")
+
+void send_with_stopwait(SOCKET sock,
+                        struct sockaddr_in6 *peer,
+                        struct packet *pkt)
+{
+    int len = sizeof(*peer);
+
+    while (1) {
+        sendto(sock, (char *)pkt, sizeof(*pkt), 0,
+               (struct sockaddr *)peer, len);
+
+        fd_set fds;
+        FD_ZERO(&fds);
+        FD_SET(sock, &fds);
+
+        TIMEVAL tv;
+        tv.tv_sec = TIMEOUT_SEC;
+        tv.tv_usec = 0;
+
+        int ret = select(0, &fds, NULL, NULL, &tv);
+        if (ret > 0) {
+            struct packet ack;
+            recvfrom(sock, (char *)&ack, sizeof(ack), 0, NULL, NULL);
+            if (ack.type == TYPE_ACK && ack.seq == pkt->seq) {
+                return;
+            }
+        }
+        printf("[timeout] retransmit\n");
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    if (argc != 2) {
+        printf("用法: %s <对方IPv6地址>\n", argv[0]);
+        return 1;
+    }
+
+    WSADATA wsa;
+    WSAStartup(MAKEWORD(2, 2), &wsa);
+
+    SOCKET sock = socket(AF_INET6, SOCK_DGRAM, 0);
+
+    struct sockaddr_in6 local = {0};
+    local.sin6_family = AF_INET6;
+    local.sin6_addr = in6addr_any;
+    local.sin6_port = htons(PORT);
+    bind(sock, (struct sockaddr *)&local, sizeof(local));
+
+    struct sockaddr_in6 peer = {0};
+    peer.sin6_family = AF_INET6;
+    peer.sin6_port = htons(PORT);
+    inet_pton(AF_INET6, argv[1], &peer.sin6_addr);
+
+    uint8_t send_seq = 0;
+    uint8_t recv_seq = 0;
+    struct packet pkt, rcv;
+
+    printf("Windows UDP IPv6 Stop-Wait Chat\n");
+
+    while (1) {
+        fd_set fds;
+        FD_ZERO(&fds);
+        FD_SET(sock, &fds);
+        TIMEVAL tv = {0, 100000};
+
+        if (select(0, &fds, NULL, NULL, &tv) > 0) {
+            recvfrom(sock, (char *)&rcv, sizeof(rcv), 0, NULL, NULL);
+            if (rcv.type == TYPE_DATA) {
+                if (rcv.seq == recv_seq) {
+                    printf("\npeer: %s\n", rcv.payload);
+                    recv_seq ^= 1;
+                }
+                rcv.type = TYPE_ACK;
+                sendto(sock, (char *)&rcv, sizeof(rcv), 0,
+                       (struct sockaddr *)&peer, sizeof(peer));
+            }
+        }
+
+        printf(">> ");
+        if (!fgets(pkt.payload, sizeof(pkt.payload), stdin))
+            break;
+
+        pkt.seq = send_seq;
+        pkt.type = TYPE_DATA;
+
+        send_with_stopwait(sock, &peer, &pkt);
+        send_seq ^= 1;
+    }
+
+    closesocket(sock);
+    WSACleanup();
+    return 0;
+}