Currently you can stream Cobain: Montage of Heck via HBO Max. You can access this streaming platform through Prime Video (we've included a link to this above), and you can try HBO Max free for 7 days. You cannot stream Cobain: Montage of Heck through Netflix or Prime Video at the moment, but if we find it streaming on those platforms in the future we will update this page.
If you don't have access to HBO Max then the only place you can buy or rent Cobain: Montage of Heck to watch online is either through iTunes or Prime Video. It will cost you $3.99 to rent the documentary and $19.99 to buy the documentary.