Droid NAS is described as 'allows you to share folders over Wi-Fi network, making your Android device visible as Bonjour computer in Finder on your Mac' and is an app in the File Sharing category. There are six alternatives to Droid NAS for a variety of platforms, including Android, Mac, Windows, Linux and Online / Web-based. The best alternative is AirDroid, which is free. Other great apps like Droid NAS are Sweech - Wifi File Transfer (Free), WiFi File Explorer Pro (Freemium), WiFi File Transfer (Freemium) and Wifi File Manager (Free).
WiFi File Transfer is a light-weight web server that lets you upload and download files to/from your phone over a wireless connection. Transfer files without a USB cable. The free version limits the file size to 5 MB
Wifi File Manager (WFM) allows you to share files from your device using any network connection, so that other devices that are reachable within the network can manage these files through user friendly interface accessed from any web browser.