Is TEFL necessary?

Hello everyone,

Honestly I don't even know where to start when it comes to gauging the validity and credibility of a company but it seems that TEFL is quite legitimate. Is it feasible to go without or should I just take the course?

Thanks!

EDIT:

I have also had some experience with Korean and Taiwanese institutions that aren't very strict about experience or certification when looking for new employees. I also see a few companies looking for French and as a French Canadian I am willing to do so as well. Additionally, I would like to stress, when it comes to teaching/living/working in Japan, I don't know even the first thing.