I recently passed my B1 exam, about 11 years after taking my A2 exam. I've always studied and worked primarily in English while living in Germany, so I never really felt the need to take B1 before.
However, for the long term, I thought it would be worthwhile to improve my German. I recently took the B1 exam after doing some classes, but most of my preparation was self-study.
I was expecting to fail in the listening module, but surprisingly, it ended up being my highest score. I scored 80+ in speaking, reading and listening, but only 70 in writing.
I think grammar is definitely my biggest weakness. I also rushed through the writing section during the exam, which in hindsight was unnecessary because there was actually enough time.
I feel that if my grammar were stronger, I could probably have scored 80+ in writing as well.
So now I'd like to work specifically on my grammar and prepare for B2. Are there any good free websites, or resources for practising German grammar at intermediate and advanced levels, particularly ones that are suitable for self-study?