World Heavy Events Association (WHEA) is the world´s first strongman/woman organizer with WADA-level anti-doping program and the athletes have committed to the clean sport principles by signing the anti-doping contract. Via the contract they are under the testing on and off competitions.
WHEA organizes yearly the World Championships for, which are named "US World Championships". In the championships, there is 4 weight classes for men and women:
-55kg, -65kg, -75kg, and 75kg+
-70kg, -85kg, -100kg, and 100kg+
There is also Masters-category for athletes over 40 years (World Championships starting 2019).
WHEA is the roof organization for national federations and organizers, which are committed to organize competitions in their home country under doping surveillance.
You can find the rules and records from the subpages.
The athltes can qualify to US World Championships via National Qualifiers (top5 per weight class gets the spot) and if there is no qualifier in the athletes country - she or he can apply a direct spot from WHEA via email.
Anyone competing in WHEA events must be member of WHEA with signed anti-doping contract no later than 3 months prior his/her first competition in WHEA.
The winners from previous years of US World Championships can be found here.