What you can analyse
DragAero is built for external aerodynamics: how air moves around a body. Below are the jobs people actually open it for. The setup is the same every time: an STL file, a speed, an angle of attack, run.
Cycling helmet
On a helmet, aerodynamics competes with ventilation and weight at the same table. Seeing the drag difference early decides which compromise is affordable.
Vehicle spoiler and diffuser
Changing a spoiler angle by one degree changes downforce and drag together. Which way and by how much is not knowable without running it.
Drone airframe
In forward flight the body and arms make drag, and drag comes straight off the flight time. Changing an arm section is cheap; measuring it is not.
Truck air deflector
On a long run, drag is fuel. How the gap between the cab and the trailer is closed matters as much as the height of the deflector on the roof.
Rooftop equipment
Anchoring a box on a roof rests on a wind load. There is a standard coefficient for it, but when the shape is not standard, seeing the real distribution helps.
Wing profile comparison
Profiles are chosen from a catalogue, but the catalogue does not say what happens at your Reynolds number and your angles.
The limit
This is a design-stage tool. Use it to compare shapes against each other and to catch obvious mistakes. For a number that goes to certification, approval or a signature, take the chosen shape to a validated solver or a wind tunnel.