Watch SAO?

I would like to watch SAO or Sword Art Online and have now arrived at season 3 (seasons 3 and 4 are not available on Netflix). Where can I watch season 3 and 4 for FREE in German except on Burning Serious? (Gerdub and not Gersub)

Nope.

There's no Gerdub any more than the fourth season.

Free and legal? Buy a Wakanim subscription (as far as I know they have seasons 3 and 4) or wait for ProSieben to show these seasons on Free TV in maybe 5 years.

PS: You can bend Gerdub with such a new anime / a new season. Maybe in 2 to 3 years.

There are only 3 seasons of the normal series, the third (Aliciziation war of underworld) being divided into 3 parts