https://maps.nextbike.net/maps/nextbike-official.json?list_cities=1
https://api.nextbike.net/maps/nextbike-live.json?apikey=&city=660&include_domains=tg%2Cde&response_type=json&show_errors=1
Source: https://github.com/chinese-soup/nextbike-mapycz/blob/master/index.html