gistfile1.txt

base = 'http://live.mobileapp.fifa.com/api/wc/'

all matches:
  base+'matches'

all teams:
  base+'teams'
  
team:
  base+'team/{ID}/en'

player:
  base+'player/{ID}/en'

match:
  base+'match/{ID}/en'

Can't find the list of match id's anywhere

GET http://live.mobileapp.fifa.com/api/wc/matches

in the json response : ['data']['group'] will give you an array of match datas, match IDs are given with the key n_MatchID.. quick python script using requests lib:

gr = requests.get('http://live.mobileapp.fifa.com/api/wc/matches').json()['data']['group']
match_ids = [m['n_MatchID'] for m in gr]

these are for the group stages