What does m/w/d or m/f/d mean in job postings in Germany?
m/w/d stands for männlich/weiblich/divers (male/female/other) and denotes the gender of the candidate that companies would like to hire for their job opening. Other alternatives are m/f/d (common for job postings in English) or any other variation (f/m/d, f/m/x, w/m/d, etc.) as to exclude männlich or male to be included in the first position. Any variation of this term is used to not discriminiate against any particular gender as that would be illegal.
In German, generally the job titles are specific towards a gender. Example: for a Software-Entwickler (Software developer) job, the job title could be written in any of the following ways.
Software-EntwicklerInnen
Software-Entwickler*innen
Software-Entwickler und Software-Entwicklerinnen
To simplify, companies usually write the title as "Softwareentwickler (m/w/d)". You can find examples with jobs containing m/w/d in Berlin. It's a sign that any gender is welcome to apply for the job even though only the masculin form of the job title is used.
This is also due to German grammar. Some companies may not explicitly want only someone from a particular gender, so they might just not mention it. Or if the job posting has the title in a different language like English, they might just say Software Developer and not mention the "m/w/d" or any variation of it.