Check if a Streamer is Live (optional PHP)

API
2

Get Streams is documented here

For example

curl -H 'Client-ID: uo6dggojyb8d6soh92zknwmi5ej1q2' \
-X GET 'https://api.twitch.tv/helix/streams?user_login=foo'

Just use a PHP cURL call and a real clientID