In your module’s .gwt.xml file:

<inherits name='com.akjava.gwt.jszip.GWTJSZip'/>

In your maven build file:

   <dependency>
      <groupId>org.ainslec</groupId>
      <artifactId>gwt-jszip</artifactId>
      <version>1.0.0</version>
      <type>gwt-lib</type>
   </dependency>

Reading files from a base64 representation of a zipfile (snippet code is public domain):

   // TODO :: Need to use other library to open file and convert byte array to base64 representation
   JSZip zipper = JSZip.loadBase64(base64Text);

   JsArrayString files = zipper.getFiles();
   int numFiles        = files.length();

   if (numFiles == 0) {
      log("Zipfile is empty");
   } else {
      for (int i=0; i < numFiles; i++) {
         String fileName          = files.get(i);
         String lowerCaseFileName = fileName.toLowerCase();
         JSFile currentFile       = zipper.getFile(fileName);
         Uint8Array data          = currentFile.asUint8Array();
         byte[] bytes1            = data.toByteArray();
         // Do something with the bytes here !
      }
   }

Saving binary data as a zipfile (snippet code is public domain):

   JSZip z = JSZip.newJSZip();
   z.file("README", "This is the content of a readme file");

   byte[] data = new byte [] {1,2,3,4,5,6,7,8,9,10};
   z.file("mybinaryfile.dat", Uint8Array.createUint8(data), null /*option*/);

   Blob generateBlob = z.generateBlob(null);

   // This is using the GWT FileSaver Wrapper Library (not part of JSZip)
   FileSaver.saveBlob("myzip.zip", generateBlob);