diff --git a/cmd/zclfmt/main.go b/cmd/zclfmt/main.go
new file mode 100644
index 0000000..17ad9f0
--- /dev/null
+++ b/cmd/zclfmt/main.go
@@ -0,0 +1,93 @@
+package main
+
+import (
+	"errors"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"os"
+
+	"github.com/zclconf/go-zcl/zclwrite"
+)
+
+const versionStr = "0.0.1-dev"
+
+var (
+	overwrite   = flag.Bool("w", false, "overwrite source files instead of writing to stdout")
+	showVersion = flag.Bool("version", false, "show the version number and immediately exit")
+)
+
+func main() {
+	if err := realmain(); err != nil {
+		fmt.Fprintln(os.Stderr, err.Error())
+		os.Exit(1)
+	}
+}
+
+func realmain() error {
+	flag.Usage = usage
+	flag.Parse()
+
+	if *showVersion {
+		fmt.Println(versionStr)
+		return nil
+	}
+
+	if flag.NArg() == 0 {
+		if *overwrite {
+			return errors.New("error: cannot use -w without source filenames")
+		}
+
+		return processFile("<stdin>", os.Stdin)
+	}
+
+	for i := 0; i < flag.NArg(); i++ {
+		path := flag.Arg(i)
+		switch dir, err := os.Stat(path); {
+		case err != nil:
+			return err
+		case dir.IsDir():
+			// This tool can't walk a whole directory because it doesn't
+			// know what file naming schemes will be used by different
+			// zcl-embedding applications, so it'll leave that sort of
+			// functionality for apps themselves to implement.
+			return fmt.Errorf("can't format directory %s", path)
+		default:
+			if err := processFile(path, nil); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+func processFile(fn string, in *os.File) error {
+	var err error
+	if in == nil {
+		in, err = os.Open(fn)
+		if err != nil {
+			return fmt.Errorf("failed to open %s: %s", fn, err)
+		}
+	}
+
+	inSrc, err := ioutil.ReadAll(in)
+	if err != nil {
+		return fmt.Errorf("failed to read %s: %s", fn, err)
+	}
+
+	outSrc := zclwrite.Format(inSrc)
+
+	if *overwrite {
+		return ioutil.WriteFile(fn, outSrc, 0644)
+	}
+
+	_, err = os.Stdout.Write(outSrc)
+	return err
+}
+
+func usage() {
+	fmt.Fprintf(os.Stderr, "usage: zclfmt [flags] [path ...]\n")
+	flag.PrintDefaults()
+	os.Exit(2)
+}