Drones weighing less than 30 kilograms are generally allowed to fly over open terrain without permission. However, you must always have direct visual contact with your aircraft when flying. In addition, there are certain situations in which you also need prior approval for smaller drones: So before you fly, make sure you check if you are really allowed to fly at this location.
Also make sure that you do not violate the privacy of other people (for example by flying low over private properties). In addition, observe the Data Protection Act: espionage and voyeurism will be punished. Accordingly, your drone may not fly over military installations or company premises, must stay away from blue-light operations and may not get closer than 5 kilometres to airfields or heliports without authorization. The same applies to so-called control zones (i.e. zones of airports and airfields that are controlled by air traffic control). Be considerate and do not endanger anyone (not even animals). It means that your drone cannot take off over nature reserves, bird sanctuaries or hunting grounds.
If your drone weighs more than 500 grams and you want to fly over a large crowd of people, you need a permit. You also need a permit if you want to fly closer than 100 metres to this group of people. This also applies to private birthday parties or wedding celebrations. And for aircraft with a flying weight of more than 30 kilograms, a prior permit from the Federal Office of Civil Aviation (FOCA) is always required.
The general regulations vary from canton to canton and from municipality to municipality. The best way to find out is to visit the FOCA website. If you want to fly an aircraft outside Switzerland, it is best to find out in advance about the regulations applicable in the country in question and whether you are adequately insured for this.