diff --git a/README.md b/README.md
index ea8c37f..8c07a04 100644
--- a/README.md
+++ b/README.md
@@ -29,6 +29,7 @@ import java.io.IOException;
 public class Compress {
   public static void main(String[] args) throws java.io.IOException {
     Tinify.setKey("YOUR_API_KEY");
+    Tinify.setProxy("http://proxy.internal.example.com") // If applicable
     Tinify.fromFile("input.png").toFile("output.png");
   }
 }
diff --git a/src/main/java/com/tinify/AccountException.java b/src/main/java/com/tinify/AccountException.java
index ca1e328..3265b66 100644
--- a/src/main/java/com/tinify/AccountException.java
+++ b/src/main/java/com/tinify/AccountException.java
@@ -4,10 +4,15 @@ public class AccountException extends Exception {
     public AccountException() {
         super();
     }
+
     public AccountException(final Throwable t) {
         super(t);
     }
-    public AccountException(final String message) { super(message); }
+
+    public AccountException(final String message) {
+        super(message);
+    }
+
     public AccountException(final String message, final String type, final int status) {
         super(message, type, status);
     }
diff --git a/src/main/java/com/tinify/Client.java b/src/main/java/com/tinify/Client.java
index 69a97b4..4043302 100644
--- a/src/main/java/com/tinify/Client.java
+++ b/src/main/java/com/tinify/Client.java
@@ -3,6 +3,10 @@
 import com.google.gson.Gson;
 import com.squareup.okhttp.*;
 import java.io.IOException;
+import java.net.Proxy;
+import java.net.InetSocketAddress;
+import java.net.Proxy.Type;
+import java.net.URL;
 import java.util.concurrent.TimeUnit;
 
 public class Client {
@@ -24,8 +28,34 @@ public enum Method {
         GET
     }
 
+    public Client(final String key) {
+        this(key, null, null);
+    }
+
     public Client(final String key, final String appIdentifier) {
+        this(key, appIdentifier, null);
+    }
+
+    public Client(final String key, final String appIdentifier, final String proxy) {
         client = new OkHttpClient();
+
+        if (proxy != null) {
+            try {
+                URL url = new URL(proxy);
+                Proxy proxyAddress = createProxyAddress(url);
+                Authenticator proxyAuthenticator = createProxyAuthenticator(url);
+
+                if (proxyAddress != null) {
+                    client.setProxy(proxyAddress);
+                    if (proxyAuthenticator != null) {
+                        client.setAuthenticator(proxyAuthenticator);
+                    }
+                }
+            } catch (java.lang.Exception e) {
+                throw new ConnectionException("Invalid proxy: " + e.getMessage(), e);
+            }
+        }
+
         client.setSslSocketFactory(SSLContext.getSocketFactory());
         client.setConnectTimeout(0, TimeUnit.SECONDS);
         client.setReadTimeout(0, TimeUnit.SECONDS);
@@ -60,6 +90,47 @@ public final Response request(final Method method, final String endpoint, final
         return request(method, endpoint, RequestBody.create(null, body));
     }
 
+    private Proxy createProxyAddress(final URL proxy) {
+        if (proxy == null) return null;
+
+        String host = proxy.getHost();
+        int port = proxy.getPort();
+
+        if (port < 0) {
+            port = proxy.getDefaultPort();
+        }
+
+        return new Proxy(Proxy.Type.HTTP, new InetSocketAddress(host, port));
+    }
+
+    private Authenticator createProxyAuthenticator(final URL proxy) {
+        if (proxy == null) return null;
+
+        String user = proxy.getUserInfo();
+        if (user == null) return null;
+
+        final String username, password;
+        int c = user.indexOf(':');
+        if (0 < c) {
+            username = user.substring(0, c);
+            password = user.substring(c + 1);
+        } else {
+            username = user;
+            password = null;
+        }
+
+        return new Authenticator() {
+            @Override public Request authenticate(Proxy proxy, Response response) throws IOException {
+                return null;
+            }
+
+            @Override public Request authenticateProxy(Proxy proxy, Response response) throws IOException {
+                String credential = Credentials.basic(username, password);
+                return response.request().newBuilder().header("Proxy-Authorization", credential).build();
+            }
+        };
+    }
+
     private Response request(final Method method, final String endpoint, final RequestBody body) throws Exception {
         HttpUrl url;
         if (endpoint.startsWith("https")) {
diff --git a/src/main/java/com/tinify/ClientException.java b/src/main/java/com/tinify/ClientException.java
index cd1b998..f759f46 100644
--- a/src/main/java/com/tinify/ClientException.java
+++ b/src/main/java/com/tinify/ClientException.java
@@ -4,9 +4,11 @@ public class ClientException extends Exception {
     public ClientException() {
         super();
     }
+
     public ClientException(final Throwable t) {
         super(t);
     }
+
     public ClientException(final String message, final String type, final int status) {
         super(message, type, status);
     }
diff --git a/src/main/java/com/tinify/ConnectionException.java b/src/main/java/com/tinify/ConnectionException.java
index 91df83f..d5e41fd 100644
--- a/src/main/java/com/tinify/ConnectionException.java
+++ b/src/main/java/com/tinify/ConnectionException.java
@@ -4,8 +4,10 @@ public class ConnectionException extends Exception {
     public ConnectionException() {
         super();
     }
+
     public ConnectionException(final Throwable t) {
         super(t);
     }
+
     public ConnectionException(final String message, final Throwable t) { super(message, t); }
 }
diff --git a/src/main/java/com/tinify/ServerException.java b/src/main/java/com/tinify/ServerException.java
index 7864224..248f3a3 100644
--- a/src/main/java/com/tinify/ServerException.java
+++ b/src/main/java/com/tinify/ServerException.java
@@ -4,9 +4,11 @@ public class ServerException extends Exception {
     public ServerException() {
         super();
     }
+
     public ServerException(final Throwable t) {
         super(t);
     }
+
     public ServerException(final String message, final String type, final int status) {
         super(message, type, status);
     }
diff --git a/src/main/java/com/tinify/Tinify.java b/src/main/java/com/tinify/Tinify.java
index 62d3d8a..5ed8f85 100644
--- a/src/main/java/com/tinify/Tinify.java
+++ b/src/main/java/com/tinify/Tinify.java
@@ -1,10 +1,12 @@
 package com.tinify;
 
 import java.io.IOException;
+import java.net.URL;
 
 public class Tinify {
     private static String key;
     private static String appIdentifier;
+    private static String proxy;
     private static int compressionCount = 0;
     private static Client client;
 
@@ -15,9 +17,9 @@ public static Client client() {
         if (client != null) {
             return client;
         } else {
-            synchronized(Tinify.class) {
+            synchronized (Tinify.class) {
                 if (client == null) {
-                    client = new Client(key(), appIdentifier());
+                    client = new Client(key, appIdentifier, proxy);
                 }
             }
             return client;
@@ -29,6 +31,11 @@ public static void setKey(final String key) {
         client = null;
     }
 
+    public static void setProxy(final String proxy) {
+        Tinify.proxy = proxy;
+        client = null;
+    }
+
     public static void setAppIdentifier(final String identifier) {
         Tinify.appIdentifier = identifier;
         client = null;
@@ -62,6 +69,10 @@ public static String key() {
         return key;
     }
 
+    public static String proxy() {
+        return proxy;
+    }
+
     public static String appIdentifier() {
         return appIdentifier;
     }
diff --git a/src/test/java/com/tinify/ClientEndpointTest.java b/src/test/java/com/tinify/ClientEndpointTest.java
index de2315d..bc728e7 100644
--- a/src/test/java/com/tinify/ClientEndpointTest.java
+++ b/src/test/java/com/tinify/ClientEndpointTest.java
@@ -22,7 +22,7 @@ public class ClientEndpointTest {
 
     @Before
     public void setup() throws IOException {
-        subject = new Client(key, null);
+        subject = new Client(key);
     }
 
     @Test
diff --git a/src/test/java/com/tinify/ClientErrorTest.java b/src/test/java/com/tinify/ClientErrorTest.java
index d34eb30..32b6d2a 100644
--- a/src/test/java/com/tinify/ClientErrorTest.java
+++ b/src/test/java/com/tinify/ClientErrorTest.java
@@ -29,7 +29,7 @@ public class ClientErrorTest {
     public void setup() throws IOException {
         Logger.getLogger(MockWebServer.class.getName()).setLevel(Level.WARNING);
         server = new MockWebServer();
-        subject = new Client(key, null);
+        subject = new Client(key);
         server.start();
     }
 
@@ -43,7 +43,7 @@ public void requestWithTimeoutShouldThrowConnectionException() throws Exception
         new Expectations() {{
             httpClient.newCall((Request) any); result = new java.net.SocketTimeoutException("SocketTimeoutException");
         }};
-        new Client(key, null).request(Client.Method.POST, "http://shrink", new byte[] {});
+        new Client(key).request(Client.Method.POST, "http://shrink", new byte[] {});
     }
 
     @Test
@@ -52,7 +52,7 @@ public void requestWithTimeoutShouldThrowExceptionWithMessage() throws Exception
             httpClient.newCall((Request) any); result = new java.net.SocketTimeoutException("SocketTimeoutException");
         }};
         try {
-            new Client(key, null).request(Client.Method.POST, "http://shrink", new byte[] {});
+            new Client(key).request(Client.Method.POST, "http://shrink", new byte[] {});
             fail("Expected an Exception to be thrown");
         } catch (ConnectionException e) {
             assertEquals("Error while connecting: SocketTimeoutException", e.getMessage());
@@ -64,7 +64,7 @@ public void requestWithSocketErrorShouldThrowConnectionException() throws Except
         new Expectations() {{
             httpClient.newCall((Request) any); result = new java.net.UnknownHostException("UnknownHostException");
         }};
-        new Client(key, null).request(Client.Method.POST, "http://shrink", new byte[] {});
+        new Client(key).request(Client.Method.POST, "http://shrink", new byte[] {});
     }
 
     @Test
@@ -73,7 +73,7 @@ public void requestWithSocketErrorShouldThrowExceptionWithMessage() throws Excep
             httpClient.newCall((Request) any); result = new java.net.UnknownHostException("UnknownHostException");
         }};
         try {
-            new Client(key, null).request(Client.Method.POST, "http://shrink", new byte[] {});
+            new Client(key).request(Client.Method.POST, "http://shrink", new byte[] {});
             fail("Expected an Exception to be thrown");
         } catch (ConnectionException e) {
             assertEquals("Error while connecting: UnknownHostException", e.getMessage());
@@ -85,7 +85,7 @@ public void requestWithUnexpectedExceptionShouldThrowConnectionException() throw
         new Expectations() {{
             httpClient.newCall((Request) any); result = new java.lang.Exception("Some exception");
         }};
-        new Client(key, null).request(Client.Method.POST, "http://shrink", new byte[] {});
+        new Client(key).request(Client.Method.POST, "http://shrink", new byte[] {});
     }
 
     @Test
@@ -94,7 +94,7 @@ public void requestWithUnexpectedExceptionShouldThrowExceptionWithMessage() thro
             httpClient.newCall((Request) any); result = new java.lang.Exception("Some exception");
         }};
         try {
-            new Client(key, null).request(Client.Method.POST, "http://shrink", new byte[] {});
+            new Client(key).request(Client.Method.POST, "http://shrink", new byte[] {});
             fail("Expected an Exception to be thrown");
         } catch (ConnectionException e) {
             assertEquals("Error while connecting: Some exception", e.getMessage());
diff --git a/src/test/java/com/tinify/ClientTest.java b/src/test/java/com/tinify/ClientTest.java
index 085d95c..214702a 100644
--- a/src/test/java/com/tinify/ClientTest.java
+++ b/src/test/java/com/tinify/ClientTest.java
@@ -14,6 +14,7 @@
 import java.io.IOException;
 import java.lang.*;
 import java.net.URISyntaxException;
+import java.net.URL;
 import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.HashMap;
@@ -35,7 +36,7 @@ public void setup() throws IOException {
 
         server = new MockWebServer();
         server.start();
-        subject = new Client(key, null);
+        subject = new Client(key);
         new MockUp<HttpUrl>()
         {
             @Mock
@@ -152,6 +153,17 @@ public void requestWhenValidWithAppIdShouldIssueRequestWithUserAgent() throws Ex
         assertEquals(Client.USER_AGENT + " TestApp/0.1", request.getHeader("User-Agent"));
     }
 
+    @Test
+    public void requestWhenValidWithProxyShouldIssueRequestWithProxyAuthorization() throws Exception, InterruptedException {
+        server.enqueue(new MockResponse().setResponseCode(407));
+        enqueuShrink();
+        Client client = new Client(key, null, "http://user:pass@" + server.getHostName() + ":" + server.getPort());
+        client.request(Client.Method.POST, "/shrink", new byte[] {});
+        RecordedRequest request1 = server.takeRequest(5, TimeUnit.SECONDS);
+        RecordedRequest request2 = server.takeRequest(5, TimeUnit.SECONDS);
+        assertEquals("Basic dXNlcjpwYXNz", request2.getHeader("Proxy-Authorization"));
+    }
+
     @SuppressWarnings("unused")
     public void requestWithTimeout() {
         // See ClientErrorTest.java
@@ -172,7 +184,7 @@ public void requestWithServerErrorShouldThrowServerException() throws Exception
         server.enqueue(new MockResponse()
                 .setResponseCode(584)
                 .setBody("{'error':'InternalServerError','message':'Oops!'}"));
-        new Client(key, null).request(Client.Method.POST, "/shrink", new byte[] {});
+        new Client(key).request(Client.Method.POST, "/shrink", new byte[] {});
     }
 
     @Test
@@ -181,7 +193,7 @@ public void requestWithServerErrorShouldThrowExceptionWithMessage() throws Excep
                 .setResponseCode(584)
                 .setBody("{'error':'InternalServerError','message':'Oops!'}"));
         try {
-            new Client(key, null).request(Client.Method.POST, "/shrink", new byte[] {});
+            new Client(key).request(Client.Method.POST, "/shrink", new byte[] {});
             fail("Expected an Exception to be thrown");
         } catch (Exception e) {
             assertEquals("Oops! (HTTP 584/InternalServerError)", e.getMessage());
@@ -193,7 +205,7 @@ public void requestWithBadServerResponseShouldThrowServerException() throws Exce
         server.enqueue(new MockResponse()
                 .setResponseCode(543)
                 .setBody("<!-- this is not json -->"));
-        new Client(key, null).request(Client.Method.POST, "/shrink", new byte[] {});
+        new Client(key).request(Client.Method.POST, "/shrink", new byte[] {});
     }
 
     @Test
@@ -202,7 +214,7 @@ public void requestWithBlankServerResponseShouldThrowServerException() throws Ex
                 .setResponseCode(543)
                 .setBody(""));
         try {
-            new Client(key, null).request(Client.Method.POST, "/shrink", new byte[] {});
+            new Client(key).request(Client.Method.POST, "/shrink", new byte[] {});
             fail("Expected an Exception to be thrown");
         } catch (Exception e) {
             assertEquals("Error while parsing response: received empty body (HTTP 543/ParseError)", e.getMessage());
@@ -215,7 +227,7 @@ public void requestWithBadServerResponseShouldThrowExceptionWithMessage() throws
                 .setResponseCode(543)
                 .setBody("<!-- this is not json -->"));
         try {
-            new Client(key, null).request(Client.Method.POST, "/shrink", new byte[] {});
+            new Client(key).request(Client.Method.POST, "/shrink", new byte[] {});
             fail("Expected an Exception to be thrown");
         } catch (Exception e) {
             assertEquals("Error while parsing response: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1 path $ (HTTP 543/ParseError)", e.getMessage());
@@ -227,7 +239,7 @@ public void requestWithClientErrorShouldThrowClientException() throws Exception
         server.enqueue(new MockResponse()
                 .setResponseCode(492)
                 .setBody("{'error':'BadRequest','message':'Oops!'}"));
-        new Client(key, null).request(Client.Method.POST, "/shrink", new byte[] {});
+        new Client(key).request(Client.Method.POST, "/shrink", new byte[] {});
     }
 
     @Test
@@ -236,7 +248,7 @@ public void requestWithClientErrorShouldThrowExceptionWithMessage() throws Excep
                 .setResponseCode(492)
                 .setBody("{'error':'BadRequest','message':'Oops!'}"));
         try {
-            new Client(key, null).request(Client.Method.POST, "/shrink", new byte[] {});
+            new Client(key).request(Client.Method.POST, "/shrink", new byte[] {});
             fail("Expected an Exception to be thrown");
         } catch (Exception e) {
             assertEquals("Oops! (HTTP 492/BadRequest)", e.getMessage());
@@ -248,7 +260,7 @@ public void requestWithBadCredentialsShouldThrowAccountException() throws Except
         server.enqueue(new MockResponse()
                 .setResponseCode(401)
                 .setBody("{'error':'Unauthorized','message':'Oops!'}"));
-        new Client(key, null).request(Client.Method.POST, "/shrink", new byte[] {});
+        new Client(key).request(Client.Method.POST, "/shrink", new byte[] {});
     }
 
     @Test
@@ -257,7 +269,7 @@ public void requestWithBadCredentialsShouldThrowExceptionWithMessage() throws Ex
                 .setResponseCode(401)
                 .setBody("{'error':'Unauthorized','message':'Oops!'}"));
         try {
-            new Client(key, null).request(Client.Method.POST, "/shrink", new byte[] {});
+            new Client(key).request(Client.Method.POST, "/shrink", new byte[] {});
             fail("Expected an Exception to be thrown");
         } catch (Exception e) {
             assertEquals("Oops! (HTTP 401/Unauthorized)", e.getMessage());
diff --git a/src/test/java/com/tinify/Integration.java b/src/test/java/com/tinify/Integration.java
index ecc9fc0..6903221 100644
--- a/src/test/java/com/tinify/Integration.java
+++ b/src/test/java/com/tinify/Integration.java
@@ -20,12 +20,14 @@ public class Integration {
     @BeforeClass
     public static void setup() throws java.io.IOException, URISyntaxException {
         String key = System.getenv().get("TINIFY_KEY");
+        String proxy = System.getenv().get("TINIFY_PROXY");
         if (key == null) {
             System.out.println("Set the TINIFY_KEY environment variable.");
             System.exit(1);
         }
 
         Tinify.setKey(key);
+        Tinify.setProxy(proxy);
 
         String unoptimizedPath = Paths.get(Integration.class.getResource("/voormedia.png").toURI()).toAbsolutePath().toString();
         optimized = Tinify.fromFile(unoptimizedPath);
diff --git a/src/test/java/com/tinify/TinifyTest.java b/src/test/java/com/tinify/TinifyTest.java
index a463e4b..029b9b4 100644
--- a/src/test/java/com/tinify/TinifyTest.java
+++ b/src/test/java/com/tinify/TinifyTest.java
@@ -52,6 +52,7 @@ HttpUrl parse(String url)
     @After
     public void tearDown() throws IOException {
         Tinify.setKey(null);
+        Tinify.setProxy(null);
         server.shutdown();
     }
 
@@ -84,6 +85,22 @@ public void appIdentifierShouldResetClientWithNewAppIdentifier() throws Interrup
         assertEquals(Client.USER_AGENT + " MyApp/2.0", request.getHeader("User-Agent"));
     }
 
+    @Test
+    public void proxyShouldResetClientWithNewProxy() throws InterruptedException {
+        server.enqueue(new MockResponse().setResponseCode(407));
+        server.enqueue(new MockResponse().setResponseCode(200));
+
+        Tinify.setKey("abcde");
+        Tinify.setProxy("http://localhost");
+        Tinify.client();
+        Tinify.setProxy("http://user:pass@" + server.getHostName() + ":" + server.getPort());
+        Tinify.client().request(Client.Method.GET, "/");
+
+        RecordedRequest request1 = server.takeRequest(5, TimeUnit.SECONDS);
+        RecordedRequest request2 = server.takeRequest(5, TimeUnit.SECONDS);
+        assertEquals("Basic dXNlcjpwYXNz", request2.getHeader("Proxy-Authorization"));
+    }
+
     @Test
     public void clientWithKeyShouldReturnClient() {
         Tinify.setKey("abcde");
@@ -95,6 +112,13 @@ public void clientWithoutKeyShouldThrowException() {
         Tinify.client();
     }
 
+    @Test(expected = ConnectionException.class)
+    public void clientWithInvalidProxyShouldThrowException() {
+        Tinify.setKey("abcde");
+        Tinify.setProxy("http-bad-url");
+        Tinify.client();
+    }
+
     @Test
     public void validateWithValidKeyShouldReturnTrue() throws InterruptedException {
         server.enqueue(new MockResponse()