Erlang/OTP 23.3 is the third maintenance patch release for OTP 23, with mostly bug fixes as well as a few improvements.
A full list of bug fixes and improvements in the readme.
Download and documentation
Online documentation can be browsed here:
https://erlang.org/documentation/doc-11.2/doc
Pre-built versions for Windows can be fetched here:
https://erlang.org/download/otp_win32_23.3.exe
https://erlang.org/download/otp_win64_23.3.exe
The Erlang/OTP source can also be found at GitHub on the official Erlang repository:
https://github.com/erlang/otp