Shootup.io is a fast paced game, so you have to learn the controls quickly. Here is a guide of all the controls.
Keep in mind that you can customize them in the settings.
Movement[]
General[]
Walk: WASD or Arrow Keys
Run: Shift Key
Open Minimap: M
In a vehicle[]
Move: Up arrow / W
Steer: Side arrows / A or D
Drift: Shift Key
Combat[]
Shoot: Click
Switch weapons: Hotbar / number keys
Build: Left click (select it) > right Click (place it) / B (select it) > right click (place it)
Interaction[]
Enter/Exit Vehicle: Space Bar
Pick up items: Space Bar
Chat: Enter Key