When it comes to Facebook they have got no competition at all really. We have smaller social networking and chat platforms like Snapchat and Tiktok but these are minnows compared to the size of the combined Facebook, Instagram and Whatsapp platforms.
Even Zuckerburg's promise to keep them separate from Facebook has now faded away as Whatsapp is to be rolled into Facebook messenger and Instagram already getting more and more of Facebook and they let you link your Instagram and Facebook accounts to let you login using just one account.