The last multi-party democratic elections held in the Weimar Republic were the March 1933 elections
https://en.wikipedia.org/wiki/March_...deral_election
In these elections the following parties participated:
The NSDAP - Nazis (extreme German nationalists who were anti-Semitic)
The SDP - Social democrats (socialists who wanted moderate reform in favour of workers rights)
The KPD - Communists (mostly Soviet sympathisers)
The Centre - German liberals and Catholics (Germany was mostly Protestant so a Catholic party won many votes from the large Catholic minority)
The DNVP - German conservatives (less extreme German nationalists)
The BVP - German liberals and Catholic Bavarian separatists.
You can note three things:
1. The elections were not exactly fair due to Nazi intimidation.
2. The SDP are clearly opponents of the Nazis, the DNVP formed a coalition with the NSDAP.
3. The only party that described itself as democratic was the SDP.
The Nazis were never a democratic party. They never used the term in the party. That word caused absolute hatred in their hearts because of the fact it was associated with Germany's defeat in WW1.