Mainz is actually quite safe or at least not more dangerous than any other average city. Just don’t talk to anyone who lingers at the main train station or in general if you’re alone at night, but there are some kebab shops that are open until quite late at night, so there’s always some people around

Very safe and calm city. Normal matters of safety are enough. Of course the usual things like cat calling at night or drunk men overstepping and being aggressive can happen when clubbing. But I feel safe most of the time.

Mainz is a very safe city all in all, sometimes you’ll see strange people but normally the won’t do anything to you, the worst they will to is make strange noises towards you when walking by or looking at you

Honestly, Mainz feels very safe to me. The worst interactions I generally have are with rude waiters, which should give you an idea of how safe the city feels to me. I walk alone at night regularly and I've never had any issues.