Major crypto libraries have adopted TLS 1.3 since its final publication in last August. Those libraries are carefully designed so the applications can switch to the new protocol with minimal code modification. However, as TLS 1.3 also brings new concepts, such as post-handshake authentication and 0-RTT, the applications needs to use new API to take full advantage of the protocol. In this presentation, we will go through the new API functions added for TLS 1.3 in multiple crypto libraries, see pros and cons of their design choices, and discuss the best practice in using those new functions.