diff --git a/cmd/zipsync/zipsync.go b/cmd/zipsync/zipsync.go
new file mode 100644
index 0000000..035a145
--- /dev/null
+++ b/cmd/zipsync/zipsync.go
@@ -0,0 +1,124 @@
+// Copyright 2018 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"archive/zip"
+	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+var (
+	outputDir  = flag.String("d", "", "output dir")
+	outputFile = flag.String("l", "", "output list file")
+	filter     = flag.String("f", "", "optional filter pattern")
+)
+
+func must(err error) {
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func writeFile(filename string, in io.Reader, perm os.FileMode) error {
+	out, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
+	if err != nil {
+		return err
+	}
+	_, err = io.Copy(out, in)
+	if err != nil {
+		out.Close()
+		return err
+	}
+
+	return out.Close()
+}
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintln(os.Stderr, "usage: zipsync -d <output dir> [-l <output file>] [-f <pattern>] [zip]...")
+		flag.PrintDefaults()
+	}
+
+	flag.Parse()
+
+	if *outputDir == "" {
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	inputs := flag.Args()
+
+	// For now, just wipe the output directory and replace its contents with the zip files
+	// Eventually this could only modify the directory contents as necessary to bring it up
+	// to date with the zip files.
+	must(os.RemoveAll(*outputDir))
+
+	must(os.MkdirAll(*outputDir, 0777))
+
+	var files []string
+	seen := make(map[string]string)
+
+	for _, input := range inputs {
+		reader, err := zip.OpenReader(input)
+		if err != nil {
+			log.Fatal(err)
+		}
+		defer reader.Close()
+
+		for _, f := range reader.File {
+			if *filter != "" {
+				if match, err := filepath.Match(*filter, filepath.Base(f.Name)); err != nil {
+					log.Fatal(err)
+				} else if !match {
+					continue
+				}
+			}
+			if filepath.IsAbs(f.Name) {
+				log.Fatal("%q in %q is an absolute path", f.Name, input)
+			}
+
+			if prev, exists := seen[f.Name]; exists {
+				log.Fatal("%q found in both %q and %q", f.Name, prev, input)
+			}
+			seen[f.Name] = input
+
+			filename := filepath.Join(*outputDir, f.Name)
+			if f.FileInfo().IsDir() {
+				must(os.MkdirAll(filename, f.FileInfo().Mode()))
+			} else {
+				must(os.MkdirAll(filepath.Dir(filename), 0777))
+				in, err := f.Open()
+				if err != nil {
+					log.Fatal(err)
+				}
+				must(writeFile(filename, in, f.FileInfo().Mode()))
+				in.Close()
+				files = append(files, filename)
+			}
+		}
+	}
+
+	if *outputFile != "" {
+		data := strings.Join(files, "\n") + "\n"
+		must(ioutil.WriteFile(*outputFile, []byte(data), 0666))
+	}
+}