Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
According to the area51 list of betas, Stack Overflow (in Portuguese) is in public beta:
Yet when clicking through, it is reported as private beta:
The latter appears correct when clicking through once more.
The site will soon move to public beta, will not fix for now.