Anyone else find it strange that Q said m/w instead of m/f?
Doing some very light digging here, not sure if this is the right direction:
Yes, you are correc that (m/w) means male/female or better männlich/weiblich.
The reason it is added is due to German antidiscrimination laws and corresponding court rulings. German has a generic masculine gender for many nouns including most professions. But it also has a specific feminine noun that can be systematically derived from the masculine one by adding -in.
• Softwareentwickler (generic masculin)
• Softwareentwicklerin (specific feminin)
https://german.stackexchange.com/questions/32107/what-does-m-f-or-m-w-mean-in-german-job-postings