The ones I go to are free and don't ask for ownership of the product, only pictures and screenshots where applicable to advertise the event. It's like working

The ones I go to are free and don't ask for ownership of the product, only pictures and screenshots where applicable to advertise the event. It's like working in a hackspace for a night (which I often do when on the road) combined with a friendly competition. I'd avoid a for-profit hackathon like the plague.