The children were with their family in Panama City Beach at a miniature golf course when a pickup truck ran off the road.
The parents, Lauren and Matt Kirchgessner, were not injured.
“A tragic accident in Panama City, Florida took the perfect, little lives of Addie and Baylor,” the fundraiser states.
Panama City Beach Police say they are investigating the incident and no charges have been filed.
The driver stayed at the scene of the crash after it happened.
The GoFundMe was set up to “help with travel expenses, funeral expenses, medical expenses, and whatever else may pop up during this terrible time.”
The family was visiting Panama City from Louisville, Kentucky.
The family said they are heartbroken but thankful for the heroes who helped after Friday’s accident.
They’ve arranged to provide meals for first responders.
“Thank you for your kindness and thoughtfulness during our darkest moments,” the family writes on the GoFundMe page.