How to send image file(binary data) using socket.io?

You can use Base64 to encode the image:

 public void sendImage(String path) { JSONObject sendData = new JSONObject(); try{ sendData.put("image", encodeImage(path)); socket.emit("message",sendData); }catch(JSONException e){ } } private String encodeImage(String path) { File imagefile = new File(path); FileInputStream fis = null; try{ fis = new FileInputStream(imagefile); }catch(FileNotFoundException e){ e.printStackTrace(); } Bitmap bm = BitmapFactory.decodeStream(fis); ByteArrayOutputStream baos = new ByteArrayOutputStream(); bm.compress(Bitmap.CompressFormat.JPEG,100,baos); byte[] b = baos.toByteArray(); String encImage = Base64.encodeToString(b, Base64.DEFAULT); //Base64.de return encImage; } 

So basically you are sending a string to node.js

If you want to receive the image just decode in Base64:

private Bitmap decodeImage(String data) { byte[] b = Base64.decode(data,Base64.DEFAULT); Bitmap bmp = BitmapFactory.decodeByteArray(b,0,b.length); return bmp; }