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.
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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.