Since the main street in the city and the main station is pretty open spaced I've always felt comfortable, even at night. There are weird people once in a while but they have always been harmless. Other areas like the Neckarwiese and Neckarstadt-West are known for being a bit more dangerous especially because of the drug use there.

Pretty safe! Just the reported crime rates are a bit high… but personally I’ve almost always felt comfortable. Just stay away from Bridges and places like the main station at night if you’re alone. If you’re out and about in Jungbusch, take the tram home with a friend ;)

You don't really have to worry if you find yourself late outside but I don't wish you tho. There are a lot of foreigners so don't worry if you can't speak german. You will find the city's really lovely.