On my local machine, I visit the url http://api.deezer.com/2.0/search/artist?q=feeder and get the correct json data returned. On my live server, I curl the same url, and get returned the json.
{"data":[],"total":0}
http status code is 200, and I don't believe I've hit the rate limit, having tested on my local machine with a similar load.
I can only suspect that someone else on the server (On a shared host here), has hit the API and got blacklisted, or they still respond when a rate limit is hit but with no notification of that fact.
Anyone got any suggestions? Currently short of waiting a few hours and trying again, I'm stumped.
(P.S. Anyone with enough rep want to make a "Deezer" tag?)
I asked this exact question to Deezer devs. The answer is that you need to have an access token to consume the data this way.
See more here: http://developers.deezer.com/api/oauth