diff --git a/web/serve.go b/web/serve.go
index 300d4b1..55d740f 100644
--- a/web/serve.go
+++ b/web/serve.go
@@ -29,6 +29,9 @@ func Serve() error {
 			return fiber.ErrBadRequest
 		}
 		url := string(urlBytes)
+		if len(url) < 1 {
+			return fiber.ErrBadRequest
+		}
 
 		meta, err := ytdl.GetMetadata(url)
 		if err != nil {
@@ -49,8 +52,43 @@ func Serve() error {
 		}, "views/layouts/main")
 	})
 
-	app.Get("/download/stream", func(c *fiber.Ctx) error {
-		return nil
+	app.Get("/download/proxy", func(c *fiber.Ctx) error {
+		urlBytes, err := url.QueryUnescape(c.Query("url"))
+		if err != nil {
+			slog.Error("Failed to decode url param", slog.String("error", err.Error()))
+			return fiber.ErrBadRequest
+		}
+		url := string(urlBytes)
+		if len(url) < 1 {
+			return fiber.ErrBadRequest
+		}
+
+		formatId := c.Query("format")
+		if len(formatId) < 1 {
+			return fiber.ErrBadRequest
+		}
+
+		meta, err := ytdl.GetMetadata(url)
+		if err != nil {
+			slog.Error("Failed to get metadata", slog.String("error", err.Error()))
+			return fiber.ErrInternalServerError
+		}
+
+		format, ok := lo.Find(meta.Formats, func(format ytdl.Format) bool {
+			return format.FormatID == formatId
+		})
+		if !ok {
+			return fiber.ErrBadRequest
+		}
+
+		c.Set("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s-%s.%s\"", meta.ID, format.Resolution, format.Ext))
+		if format.Filesize != nil {
+			c.Set("Content-Length", fmt.Sprint(*format.Filesize))
+		} else if format.FilesizeApprox != nil {
+			c.Set("Content-Length", fmt.Sprint(*format.FilesizeApprox))
+		}
+
+		return ytdl.Stream(c.Response().BodyWriter(), url, format)
 	})
 
 	listenAddr := fmt.Sprintf("%s:%d", viper.GetString("listen"), viper.GetInt("port"))
diff --git a/ytdl/data.go b/ytdl/data.go
index bbd6ff2..82dcc21 100644
--- a/ytdl/data.go
+++ b/ytdl/data.go
@@ -252,7 +252,7 @@ type Format struct {
 	Filesize *int `json:"filesize"`
 
 	// An estimate for the number of bytes
-	FilesizeApprox int `json:"filesize_approx"`
+	FilesizeApprox *int `json:"filesize_approx"`
 
 	// The protocol that will be used for the actual
 	// download, lower-case. One of "http", "https" or
diff --git a/ytdl/meta.go b/ytdl/meta.go
index 06a13db..b643d6d 100644
--- a/ytdl/meta.go
+++ b/ytdl/meta.go
@@ -17,7 +17,7 @@ func GetMetadata(url string) (Metdata, error) {
 	cmd.Stdout = &out
 
 	if err := cmd.Run(); err != nil {
-		return Metdata{}, nil
+		return Metdata{}, err
 	}
 
 	var meta Metdata
diff --git a/ytdl/stream.go b/ytdl/stream.go
new file mode 100644
index 0000000..b6f7f2a
--- /dev/null
+++ b/ytdl/stream.go
@@ -0,0 +1,23 @@
+package ytdl
+
+import (
+	"io"
+	"os/exec"
+)
+
+func Stream(wr io.Writer, url string, format Format) error {
+	cmd := exec.Command(
+		"yt-dlp",
+		"-o", "-",
+		"-f", format.FormatID,
+		"--merge-output-format", "mkv",
+		url,
+	)
+
+	cmd.Stdout = wr
+	if err := cmd.Run(); err != nil {
+		return err
+	}
+
+	return nil
+}