diff --git a/README.md b/README.md
index 9e2fec9..2e9d2c2 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,7 @@
 - [ ] Uploader
     - [ ] mapping IA S3 protocol
     - [ ] modify metadata
+- [ ] Version check
 - [ ] CLI
     - [X] `aixifan_config.json` Config
         - [x] "downloads_home_dir"
diff --git a/main.go b/main.go
index 800b554..1dafa3a 100644
--- a/main.go
+++ b/main.go
@@ -3,19 +3,23 @@ package main
 import (
 	"flag"
 	"fmt"
+	"log/slog"
 	"os"
 
 	"github.com/saveweb/aixifan/pkg/config"
 	"github.com/saveweb/aixifan/pkg/downloader"
+	"github.com/saveweb/aixifan/pkg/utils"
 )
 
 func help() {
+	fmt.Println("aixifan - " + utils.GetVersion().Version + " (" + utils.GetVersion().GoVersion + ")")
 	fmt.Println(
-		`Usage: aixifan action dougaId
+		`Usage: aixifan action [dougaId]
 
 Action:
   down  Download
   up    Upload to IA
+  version  Show version
 dougaId:
   int-string, NOT contain 'ac' or '_'
 
@@ -26,30 +30,30 @@ e.g. aixifan down 32749`)
 func main() {
 	flag.Usage = help
 	flag.Parse()
-	if flag.NArg() < 2 {
-		help()
-		os.Exit(1)
-	}
 
 	action := flag.Arg(0)
-	dougaId := flag.Arg(1)
-
-	config, err := config.LoadOrNewConfig()
-	if err != nil {
-		panic(err)
-	}
-	if err := config.MakeDownloadsHomeDir(); err != nil {
-		panic(err)
-	}
 
 	switch action {
 	case "down":
+		dougaId := flag.Arg(1)
+		config, err := config.LoadOrNewConfig()
+		if err != nil {
+			panic(err)
+		}
+		if err := config.MakeDownloadsHomeDir(); err != nil {
+			panic(err)
+		}
+
 		if err := downloader.Download(config.DownloadsHomeDir, dougaId); err != nil {
 			panic(err)
 		}
 	case "up":
 		panic("not implemented")
+	case "version":
+		fmt.Println(utils.GetVersion().Version)
 	default:
-		panic("unknown action")
+		slog.Error("Invalid action")
+		help()
+		os.Exit(2)
 	}
 }
diff --git a/pkg/api/api.go b/pkg/api/api.go
index 51c8f06..8251c8c 100644
--- a/pkg/api/api.go
+++ b/pkg/api/api.go
@@ -9,6 +9,7 @@ import (
 	"strings"
 
 	"github.com/saveweb/aixifan/pkg/extractor"
+	"github.com/saveweb/aixifan/pkg/utils"
 	"github.com/tidwall/gjson"
 )
 
@@ -19,7 +20,7 @@ func requestDouga(client *http.Client, acId string) ([]byte, error) {
 	}
 	url := "https://www.acfun.cn/v/ac" + acId + "?quickViewId=videoInfo_new&ajaxpipe=1"
 	req, err := http.NewRequest("GET", url, nil)
-	req.Header.Set("User-Agent", "aixifanfan/0.0.1")
+	req.Header.Set("User-Agent", "aixifanfan/"+utils.GetVersion().Version)
 
 	resp, err := client.Do(req)
 	if err != nil {
diff --git a/pkg/downloader/downloader.go b/pkg/downloader/downloader.go
index a97d4be..2f2872a 100644
--- a/pkg/downloader/downloader.go
+++ b/pkg/downloader/downloader.go
@@ -12,10 +12,11 @@ import (
 	"github.com/saveweb/aixifan/pkg/api"
 	"github.com/saveweb/aixifan/pkg/extractor"
 	"github.com/saveweb/aixifan/pkg/ffmpeg"
+	"github.com/saveweb/aixifan/pkg/utils"
 )
 
 var headers = map[string]string{
-	"User-Agent": "aixifanfan/0.0.1",
+	"User-Agent": "aixifanfan/" + utils.GetVersion().Version,
 }
 
 func validateDougaId(dougaId string) bool {
diff --git a/pkg/utils/version.go b/pkg/utils/version.go
new file mode 100644
index 0000000..baf1c25
--- /dev/null
+++ b/pkg/utils/version.go
@@ -0,0 +1,28 @@
+package utils
+
+import "runtime/debug"
+
+type Version struct {
+	Version   string
+	GoVersion string
+}
+
+// copy from github.com/internetarchive/Zeno (AGPLv3)
+func GetVersion() (version Version) {
+	version.Version = "unknown_version"
+	if info, ok := debug.ReadBuildInfo(); ok {
+		for _, setting := range info.Settings {
+			if setting.Key == "vcs.revision" {
+				version.Version = setting.Value
+			}
+
+			if setting.Key == "vcs.modified" {
+				if setting.Value == "true" {
+					version.Version += " (modified)"
+				}
+			}
+		}
+		version.GoVersion = info.GoVersion
+	}
+	return
+}