I find Quantopian is a pretty good testbed given you can get their stock data for free in their contests.<p>No need for a brokerage account, minimum, or any sort of fee.<p><a href="https:&#x2F;&#x2F;www.quantopian.com&#x2F;open" rel="nofollow">https:&#x2F;&#x2F;www.quantopian.com&#x2F;open</a>