To install, add wagtail.contrib.wagtailapi and rest_framework to INSTALLED_APPS in your Django settings and configure a URL for it in urls.py:
# settings.py
INSTALLED_APPS = [
...
'wagtail.contrib.wagtailapi',
'rest_framework',
]
# urls.py
from wagtail.contrib.wagtailapi import urls as wagtailapi_urls
urlpatterns = [
...
url(r'^api/', include(wagtailapi_urls)),
...
# Ensure that the wagtailapi_urls line appears above the default Wagtail page serving route
url(r'', include(wagtail_urls)),
]