You can watch "Only Fools and Horses" streaming on ITVX Premium and Now TV. It is also available for purchase as a download on Apple TV and Amazon Video. There are no free streaming options currently available for this show.

Additionally, some episodes and clips are available on YouTube channels like BBC Comedy Greats, but full official streaming access is mainly through ITVX Premium and Now TV.

There is also a user-uploaded full series collection on archive.org, but for official and reliable viewing, the above platforms are recommended.