The BT stack is based on Bluedroid, so that’s open source (up to the driver I’d guess); see here https://github.com/espressif/esp-idf/tree/master/components/bt/

The BT stack is based on Bluedroid, so that’s open source (up to the driver I’d guess); see here https://github.com/espressif/esp-idf/tree/master/components/bt/host/bluedroid https://github.com/espressif/esp-idf/tree/master/components/...