It is a city where one must be primarily cautious; it is not so bad to walk on the street at night, but only if it is in busy places. The train (or subway) is the most comfortable means of transport to use considering the risks, I would say that buses (or taxis) come as the second option because the level of mobility around the city is good and there is not too much risk in using them, but they are very expensive. I would put the buses (or minibuses) last; they are the ones with the highest risk of being robbed or sexually harassed. The good thing is that there are police stations in several areas, so if there is any problem you can run to one.

Its better than Santiago for sure but theres always the possibility of something happening even more in places with more commerce and people like the center or dangerous neighborhoods but nothing close to the city attractions. Valparaiso gets more dangerous at night for sure but ive been there to party and all and nothing has ever happened to me luckily.

During the day, it is completely fine, but I would advise against going out at night alone, especially in winter. In the summer, it is safer since it gets dark later on in the night, but I would still advise not to go out alone since there's a higher rate of mugging.

Beautiful, but can be dangerous, you need to keep your eyes open around, don't walk with cell in your hand. Don't walk around at night alone. Especially if you don't look latina , people might pester you. Be careful of pick pockets. But overall people are friendly and willing to help and many beautiful places to see.