diff --git a/README.md b/README.md
index 7e4c3c7..87abb0c 100644
--- a/README.md
+++ b/README.md
@@ -106,7 +106,7 @@ To use this library you need to ensure you are using the correct version of Reac
 
 | `react-native-tcp-socket` version         | Required React Native Version                                                     |
 | ----------------------------------------- | --------------------------------------------------------------------------------- |
-| `3.x.x`                                   | `>= 0.61`                                                                         |
+| `4.X.X`, `3.X.X`                                   | `>= 0.61`                                                                         |
 | `1.2.2`                                   | `>= 0.??`                                                                         |
 
 ## Usage
@@ -184,10 +184,13 @@ Here are listed all methods implemented in `react-native-tcp-socket`, their func
 ### TcpSocket
 * **Methods:**
   * **[`TcpSocket.createConnection(options[, callback])`](#createconnection)**
-  * [`write(data[, encoding][, callback])`](https://nodejs.org/api/net.html#net_socket_write_data_encoding_callback)
+  * [`address()`](https://nodejs.org/api/net.html#net_socket_address)
   * [`destroy([error])`](https://nodejs.org/api/net.html#net_socket_destroy_error)
+  * [`end([data][, encoding][, callback])`](https://nodejs.org/api/net.html#net_socket_end_data_encoding_callback)
+  * [`setKeepAlive([enable][, initialDelay])`](https://nodejs.org/api/net.html#net_socket_setkeepalive_enable_initialdelay) - _`initialDelay` is ignored_
   * [`setNoDelay([noDelay])`](https://nodejs.org/api/net.html#net_socket_setnodelay_nodelay)
   * [`setTimeout(timeout[, callback])`](https://nodejs.org/api/net.html#net_socket_settimeout_timeout_callback)
+  * [`write(data[, encoding][, callback])`](https://nodejs.org/api/net.html#net_socket_write_data_encoding_callback)
 
 #### `createConnection()`
 `createConnection(options[, callback])` creates a TCP connection using the given [`options`](#createconnection-options).
diff --git a/android/src/main/java/com/asterinet/react/tcpsocket/TcpSocketClient.java b/android/src/main/java/com/asterinet/react/tcpsocket/TcpSocketClient.java
index 371e974..30926d8 100644
--- a/android/src/main/java/com/asterinet/react/tcpsocket/TcpSocketClient.java
+++ b/android/src/main/java/com/asterinet/react/tcpsocket/TcpSocketClient.java
@@ -141,4 +141,15 @@ public void setNoDelay(final boolean noDelay) throws IOException {
         }
         socket.setTcpNoDelay(noDelay);
     }
+
+    /**
+     * @param enable `true` to enable keep-alive functionality
+     */
+    public void setKeepAlive(final boolean enable, final int initialDelay) throws IOException {
+        if (socket == null) {
+            throw new IOException("Socket is not connected.");
+        }
+        // `initialDelay` is ignored
+        socket.setKeepAlive(enable);
+    }
 }
diff --git a/android/src/main/java/com/asterinet/react/tcpsocket/TcpSocketModule.java b/android/src/main/java/com/asterinet/react/tcpsocket/TcpSocketModule.java
index a8c437b..6da6153 100644
--- a/android/src/main/java/com/asterinet/react/tcpsocket/TcpSocketModule.java
+++ b/android/src/main/java/com/asterinet/react/tcpsocket/TcpSocketModule.java
@@ -164,6 +164,7 @@ protected void doInBackgroundGuarded(Void... params) {
         }.executeOnExecutor(executorService);
     }
 
+    @SuppressWarnings("unused")
     @ReactMethod
     public void setNoDelay(@NonNull final Integer cId, final boolean noDelay) {
         final TcpSocketClient client = socketClients.get(cId);
@@ -178,6 +179,21 @@ public void setNoDelay(@NonNull final Integer cId, final boolean noDelay) {
         }
     }
 
+    @SuppressWarnings("unused")
+    @ReactMethod
+    public void setKeepAlive(@NonNull final Integer cId, final boolean enable, final int initialDelay) {
+        final TcpSocketClient client = socketClients.get(cId);
+        if (client == null) {
+            onError(cId, TAG + "socket not found.");
+            return;
+        }
+        try {
+            client.setKeepAlive(enable, initialDelay);
+        } catch (IOException e) {
+            onError(cId, e.getMessage());
+        }
+    }
+
     private void requestNetwork(final int transportType) throws InterruptedException {
         final NetworkRequest.Builder requestBuilder = new NetworkRequest.Builder();
         requestBuilder.addTransportType(transportType);
diff --git a/examples/tcpsockets/ios/Podfile.lock b/examples/tcpsockets/ios/Podfile.lock
index cab7a23..f3eac35 100644
--- a/examples/tcpsockets/ios/Podfile.lock
+++ b/examples/tcpsockets/ios/Podfile.lock
@@ -233,7 +233,7 @@ PODS:
     - React-cxxreact (= 0.62.1)
     - React-jsi (= 0.62.1)
   - React-jsinspector (0.62.1)
-  - react-native-tcp-socket (3.4.2):
+  - react-native-tcp-socket (4.1.0):
     - CocoaAsyncSocket
     - React
   - React-RCTActionSheet (0.62.1):
@@ -430,7 +430,7 @@ SPEC CHECKSUMS:
   React-jsi: 600d8e42510c3254fd2abd702f4b9d3f598d8f52
   React-jsiexecutor: e9698dee4fd43ceb44832baf15d5745f455b0157
   React-jsinspector: f74a62727e5604119abd4a1eda52c0a12144bcd5
-  react-native-tcp-socket: a100fffbe7c96f92f457fa7fad6a29ec24bb8187
+  react-native-tcp-socket: 7ae44fe823a4c8e73f66e4562fceef392f94ce13
   React-RCTActionSheet: af8f28dd82fec89b8fe29637b8c779829e016a88
   React-RCTAnimation: 0d21fff7c20fb8ee41de5f2ebb63221127febd96
   React-RCTBlob: 9496bd93130b22069bfbc5d35e98653dae7c35c6
diff --git a/examples/tcpsockets/package.json b/examples/tcpsockets/package.json
index 69683bc..ccee04a 100644
--- a/examples/tcpsockets/package.json
+++ b/examples/tcpsockets/package.json
@@ -14,7 +14,7 @@
   "dependencies": {
     "react": "16.11.0",
     "react-native": "0.62.1",
-    "react-native-tcp-socket": "^3.5.0"
+    "react-native-tcp-socket": "^4.1.0"
   },
   "devDependencies": {
     "@babel/core": "^7.7.2",
diff --git a/ios/TcpSocketClient.h b/ios/TcpSocketClient.h
index 672ee89..2c1b3b8 100644
--- a/ios/TcpSocketClient.h
+++ b/ios/TcpSocketClient.h
@@ -94,4 +94,6 @@ typedef enum RCTTCPError RCTTCPError;
 
 - (void)setNoDelay:(BOOL)noDelay;
 
+- (void)setKeepAlive:(BOOL)enable initialDelay:(int)initialDelay;
+
 @end
diff --git a/ios/TcpSocketClient.m b/ios/TcpSocketClient.m
index a6105f2..bbcbb0d 100644
--- a/ios/TcpSocketClient.m
+++ b/ios/TcpSocketClient.m
@@ -132,7 +132,21 @@ - (void)setNoDelay:(BOOL)noDelay
         int on = noDelay ? 1 : 0;
         if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, (char*)&on, sizeof(on)) == -1) {
             /* TODO: handle error */
-            RCTLogWarn(@"setNoDelay caused an unexpected error");
+            RCTLogWarn(@"react-native-tcp-socket: setNoDelay() caused an unexpected error");
+        }
+    }];
+}
+
+- (void)setKeepAlive:(BOOL)enable initialDelay:(int)initialDelay
+{
+    [_tcpSocket performBlock:^{
+        int fd = [self->_tcpSocket socketFD];
+        int on = enable ? 1 : 0;
+        int enableKA = setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on));
+        // `initialDelay` is ignored
+        if (enableKA == -1) {
+            /* TODO: handle error */
+            RCTLogWarn(@"react-native-tcp-socket: setKeepAlive() caused an unexpected error");
         }
     }];
 }
diff --git a/ios/TcpSockets.m b/ios/TcpSockets.m
index 166ea54..5666e30 100644
--- a/ios/TcpSockets.m
+++ b/ios/TcpSockets.m
@@ -123,6 +123,13 @@ - (TcpSocketClient *)createSocket:(nonnull NSNumber*)cId
     [client setNoDelay:noDelay];
 }
 
+RCT_EXPORT_METHOD(setKeepAlive:(nonnull NSNumber*)cId enable:(BOOL)enable initialDelay:(int)initialDelay) {
+    TcpSocketClient* client = [self findClient:cId];
+    if (!client) return;
+    
+    [client setKeepAlive:enable initialDelay:initialDelay];
+}
+
 - (void)onConnect:(TcpSocketClient*) client
 {
     [self sendEventWithName:@"connect"
diff --git a/src/TcpSocket.js b/src/TcpSocket.js
index fb70202..aa0a206 100644
--- a/src/TcpSocket.js
+++ b/src/TcpSocket.js
@@ -162,10 +162,39 @@ export default class TcpSocket extends EventEmitter {
      *
      * Passing `true` for `noDelay` or not passing an argument will disable Nagle's algorithm for the socket. Passing false for noDelay will enable Nagle's algorithm.
      *
-     * @param {boolean} noDelay
+     * @param {boolean} noDelay Default: `true`
      */
     setNoDelay(noDelay = true) {
+        if (this._state != STATE.CONNECTED) {
+            this.once('connect', () => this.setNoDelay(noDelay));
+            return this;
+        }
         Sockets.setNoDelay(this._id, noDelay);
+        return this;
+    }
+
+    /**
+     * Enable/disable keep-alive functionality, and optionally set the initial delay before the first keepalive probe is sent on an idle socket.
+     *
+     * `initialDelay` is ignored.
+     *
+     * @param {boolean} enable Default: `false`
+     * @param {number} initialDelay ***IGNORED**. Default: `0`
+     */
+    setKeepAlive(enable = false, initialDelay = 0) {
+        if (this._state != STATE.CONNECTED) {
+            this.once('connect', () => this.setKeepAlive(enable, initialDelay));
+            return this;
+        }
+
+        if (initialDelay !== 0) {
+            console.warn(
+                'react-native-tcp-socket: initialDelay param in socket.setKeepAlive() is ignored'
+            );
+        }
+
+        Sockets.setKeepAlive(this._id, enable, Math.floor(initialDelay));
+        return this;
     }
 
     address() {