The best alternatives to Buddy Finder are Adidas Runtastic, Fitspur, and GYMDER. If these 3 options don't work for you, we've listed a few more alternatives below.
adidas Running by Runtastic or formerly named Runtastic is an Austrian mobile fitness company that combines traditional fitness with mobile applications, social networking and elements of gamification as a logical reaction to the Quantified Self movement.
Sportbadi is a free website where you can find partners to practice any sport. You can join existing groups or create your own one. Similar to Meetup but 100% free and only especialized in sports. https://sportbadi.com
TrimAlly is a social fitness app, designed to arrange workouts by connecting you with others who are looking for a workout partner. Enter your workout details and TrimAlly will return a list of matches. You can also keep up to date and in contact via the app.