GEKKO is an up-to-date BTC trading bot under MIT license. It supports a wide range of trading sites already including very popular ones like Poloniex. Additionally, you could write simple scripts yourself to automate trades on sites with APIs that are not in Gekko's list. I wrote an on-site Ruby
tutorial for beginners. It should work fine with upcoming trading sites like TuxExchange. I warn you, though, automatic bots are supposed to automate the steps that you would do manually. You still should have the idea of the basics first. Also, I advise you to consider that, in spite of the precise and quick algorithms, there is no guarantee on the amount of your profit especially with small investments.