Swansea boss Michael Laudrup says it is likely he will bring in a goalkeeper in January as Michel Vorm needs knee surgery.
Manager Jose Mourinho believes Ashley Cole will earn a contract extension at Chelsea.
The 21-year-old had over a year left to run on his existing deal but the club were keen to tie him to a longer-term agreement.
Alfei, who has spent most of the season on loan at Wrexham, said: "I'm absolutely delighted. It's good to know the club has faith in me and there is nowhere I would rather be than Swansea."