Kadar has been playing at international World Darts Federation tournaments since 2010, made his debut at the 2010 WDF Europe Cup, where he was defeated by a whitewash in his opening game against Christian Demazure.

In his subsequent 2010 Winmau World Masters debut, Kadar won his first game against Peter Holczer before losing to Dennis Harbour in the third round.

In 2011, Kadar took part in the 2011 WDF World Cup for the first time, winning his first game against Kevin Jacob 4–3 in legs.

He landed a bigger success at the 2014 WDF Europe Cup, where it went to the third round in singles competition, but lost 0–4 to Ross Montgomery.

Kadar survived match darts and advanced to second round, but failed to win a set against Richard Veenstra.