How to just check if a channel is live?

Doesn’t seem to work as simply as that.

Switching to helix, so doing:

https://api.twitch.tv/helix/streams?client_id=id&channel=name (where id is the ID from my Client ID in the dev dashboard for my “app”)

Always gives me:

{“error”:“Unauthorized”,“status”:401,“message”:“Must provide a valid Client-ID or OAuth token”}