diff --git a/src/main/java/com/sendgrid/SendGrid.java b/src/main/java/com/sendgrid/SendGrid.java
index 897728bc..d47fcedf 100644
--- a/src/main/java/com/sendgrid/SendGrid.java
+++ b/src/main/java/com/sendgrid/SendGrid.java
@@ -5,10 +5,10 @@
 import java.util.Map;
 
 /**
- * Class SendGrid allows for quick and easy access to the SendGrid API.
- */
-public class SendGrid {
-  /** The current library version. */
+  * Class SendGrid allows for quick and easy access to the SendGrid API.
+  */
+public class SendGrid implements SendGridAPI {
+
   private static final String VERSION = "3.0.0";
 
   /** The user agent string to return to SendGrid. */
diff --git a/src/main/java/com/sendgrid/SendGridAPI.java b/src/main/java/com/sendgrid/SendGridAPI.java
new file mode 100644
index 00000000..32998459
--- /dev/null
+++ b/src/main/java/com/sendgrid/SendGridAPI.java
@@ -0,0 +1,92 @@
+package com.sendgrid;
+
+import java.io.IOException;
+import java.util.Map;
+
+public interface SendGridAPI {
+
+  /**
+   * Initializes SendGrid
+   * 
+   * @param apiKey is your SendGrid API Key: https://app.sendgrid.com/settings/api_keys
+   */
+  public void initializeSendGrid(String apiKey);
+
+  /**
+   * Returns the library version
+   * 
+   * @param apiKey is your SendGrid API Key: https://app.sendgrid.com/settings/api_keys
+   * @return the library version.
+   */
+  public String getLibraryVersion();
+
+  /**
+   * Gets the version.
+   *
+   * @return returns the version.
+   */
+  public String getVersion();
+
+  /**
+   * Sets the version.
+   * 
+   * @param version the SendGrid version.
+   */
+  public void setVersion(String version);
+
+  /**
+   * Gets the request headers.
+   * @return returns a map of request headers.
+   */
+  public Map<String, String> getRequestHeaders();
+
+  /**
+   * Adds a request headers.
+   * 
+   * @param key the key
+   * @param value the value
+   * @return returns a map of request headers.
+   */
+  public Map<String, String> addRequestHeader(String key, String value);
+
+  /**
+   * Removes a request headers.
+   * 
+   * @param key the key
+   * @return returns a map of request headers.
+   */
+  public Map<String, String> removeRequestHeader(String key);
+
+  /**
+   * Gets the host.
+   * 
+   * @return returns the host.
+   */
+  public String getHost();
+
+  /**
+   * Sets the host.
+   * 
+   * @param host the host to set
+   */
+  public void setHost(String host);
+
+  /**
+   * Class makeCall makes the call to the SendGrid API, override this method for
+   * testing.
+   * 
+   * @param request the request
+   * @return returns a response.
+   * @throws IOException in case of network or marshal error.
+   */
+  public Response makeCall(Request request) throws IOException;
+
+  /**
+   * Class api sets up the request to the SendGrid API, this is main interface.
+   * 
+   * @param request the request
+   * @return returns a response.
+   * @throws IOException in case of network or marshal error.
+   */
+  public Response api(Request request) throws IOException;
+}