A free program for Android, by Nordic Semiconductor ASA.

The nRF Toolbox is an Android app for the remote control of Bluetooth Low Energy (BLE) devices using the nRF5 Bluetooth chip from Nordic Semiconductor.

The nRF Toolbox is a convenient location for storing your Nordic Semiconductor Bluetooth Low Energy apps. It includes applications that demonstrate a variety of Bluetooth LE profiles, including cycling speed and cadence, running speed and cadence, heart rate monitor, blood pressure monitor, health thermometer monitor, and glucose monitor.

The DFU tool is perfect for transferring firmware and applications to devices in DFU mode. It makes it easy to upload files directly to your phone or tablet, and you can pause, resume, and cancel uploads if needed. Plus, it comes with pre-installed examples so you can get started right away.