diff --git a/backend/bridge.go b/backend/bridge.go
index ea39e169..41359e6f 100644
--- a/backend/bridge.go
+++ b/backend/bridge.go
@@ -14,6 +14,7 @@ import (
 	"github.com/chaitin/MonkeyCode/backend/domain"
 	"github.com/chaitin/MonkeyCode/backend/errcode"
 	"github.com/chaitin/MonkeyCode/backend/pkg"
+	"github.com/chaitin/MonkeyCode/backend/pkg/captcha"
 	"github.com/chaitin/MonkeyCode/backend/pkg/tasker"
 )
 
@@ -84,6 +85,12 @@ func WithSiteResolver(resolver domain.SiteResolver) BridgeOption {
 	}
 }
 
+func WithCaptcha(captcha *captcha.Captcha) BridgeOption {
+	return func(i *do.Injector) {
+		do.OverrideValue(i, captcha)
+	}
+}
+
 func Register(e *echo.Echo, dir string, opts ...BridgeOption) error {
 	cfg, err := config.Init(dir)
 	if err != nil {