Johan Kanflo’s Esprog pogo pin connector:
The FTDI connector can be found on just about any ESP8266 design. If you are building a gadget to be deployed somewhere and not a full blown development board, the FTDI connector is somewhat overkill. And it is quite large. A few pins could be shaved off but we still have a through hole connector invading the other side of the PCB. I ended up designing my own connector and it has been used sucessfully in all of my recent projects.
Factory programming ESP8266 gadgets – [Link]