Santos is very safe compared to the cities that surround it - São Vicente, Guarujá and Cubatão. You have to be aware but it isn’t that desperate, you can chill and enjoy your time walking around. It isn’t a big city like São Paulo, so usually the nigh life isn’t that strong, which ends um leaving the streets quite empty at night. Depending on the season, the streets will be more crowded when the sun goes down next to the beach, but when it gets to 23h/00h, you won’t see too many people walking...

Santos is a really nice city if you got to way to walk around, just be careful with guys in bikes trying to steal your phone and try to be the most low as possible to not get attention. But by the beach is usually more safer and very lighting!