Internal Transfers via API

API Spot/Margin API
1

How can I access internal transfers via the API?

These are transfers done between 2 accounts which are not related (i.e. sub/master). The functionality is described here: How to Make Internal Transfer on Binance | Binance

2

You can do the withdrawal via POST /sapi/v1/capital/withdraw/apply

If it’s master/sub-account, you can consider POST /sapi/v1/sub-account/universalTransfer