You can use the stdlib (json & urllib2) to avoid the use of external commands:
import json
import urllib2
url = "http://httpbin.org/get"
response = urllib2.urlopen(url)
data = response.read()
values = json.loads(data)
But I'd recommend to use requests to simplify your code. Here a sample from the docs:
import requests
r = requests.get('https://api.github.com/user', auth=('user', 'pass'))
r.status_code
200
r.headers['content-type']
'application/json; charset=utf8'
r.encoding
'utf-8'
r.text
u'{"type":"User"...'
r.json()
{u'private_gists': 419, u'total_private_repos': 77, ...}
Python 3 Update
Please consider that in Python3 urllib2 does not exists anymore, you should use urllib which comes in the standard library
req = urllib.request.Request(url)
response = urllib.request.urlopen(req)
data = response.read()
values = json.loads(data)