Seinfeld was a huge show when it came out and it still is, and for a show that is nearly 30 years old the show obviously still has legs. So much so that Netflix has paid $500 million for the streaming rights to the show, which will be added in 2021. Netflix will have the rights for 5 years.

I know in the UK, the entirety of the show is currently available on Amazon Prime Video but the Netflix deal is a global one, so every country will get access.

Source: Netflix (Twitter)