I have no own experience with IG and I am not affiliated with them, so I cannot and do not want to comment on their quality/integrity - but the API and the # of tradable instruments seem interesting for automation. They also have binary options and might be at least one of the less dubious binary options brokers out there that could be used for the system described by jcl (http://www.financial-hacker.com/binary-options-scam-or-opportunity/).