diff --git a/commands/commands.go b/commands/commands.go
index 75b8c72d..69f52444 100644
--- a/commands/commands.go
+++ b/commands/commands.go
@@ -52,4 +52,5 @@ var CommandMap = map[string]*Command{
 	"request": requestCmd,
 	"show":    showCmd,
 	"submit":  submitCmd,
+	"web":     webCmd,
 }
diff --git a/commands/web.go b/commands/web.go
new file mode 100644
index 00000000..4b258e18
--- /dev/null
+++ b/commands/web.go
@@ -0,0 +1,74 @@
+package commands
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"os/exec"
+	"runtime"
+	"strconv"
+	"sync"
+
+	"github.com/google/git-appraise/repository"
+)
+
+var webFlagSet = flag.NewFlagSet("web", flag.ExitOnError)
+
+var (
+	webPort = webFlagSet.Int("port", 12345, "Port to run git-appraise-web.")
+)
+
+func openBrowser(url string) error {
+	var err error
+
+	switch runtime.GOOS {
+	case "linux":
+		err = exec.Command("xdg-open", url).Start()
+	case "windows":
+		err = exec.Command("rundll32", "url.dll,FileProtocolHandler", url).Start()
+	case "darwin":
+		err = exec.Command("open", url).Start()
+	default:
+		err = fmt.Errorf("unsupported platform")
+	}
+	return err
+}
+
+func openWeb(args []string) error {
+	webFlagSet.Parse(args)
+
+	bin, err := exec.LookPath("git-appraise-web")
+	if err != nil {
+		return err
+	}
+
+	cmd := exec.Command(bin, "-port", strconv.Itoa(*webPort))
+	cmd.Stderr = os.Stderr
+	cmd.Stdout = os.Stdout
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		fmt.Printf("starting %s on http://localhost:%d\n", bin, *webPort)
+		err = cmd.Run()
+		wg.Done()
+	}()
+
+	if err = openBrowser(fmt.Sprintf("http://localhost:%d", *webPort)); err != nil {
+		return err
+	}
+
+	wg.Wait()
+	return err
+}
+
+// rejectCmd defines the "reject" subcommand.
+var webCmd = &Command{
+	Usage: func(arg0 string) {
+		fmt.Printf("Usage: %s web [<option>...]\n\nOptions:\n", arg0)
+		webFlagSet.PrintDefaults()
+	},
+	RunMethod: func(_ repository.Repo, args []string) error {
+		return openWeb(args)
+	},
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 00000000..8df4ceda
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/google/git-appraise
+
+go 1.14