We all run tests on safe, separate test environments. But what if let them loose on production systems? Is that dangerous, or is it worth the risk? This can seem daunting, but there are huge benefits. I’ll discuss some of the downsides to testing in isolated, unrepresentative test environments, before talking about my experiences of using Selenium to test in production as much as possible. I’ll demonstrate the benefits, like how we can turn automated tests into monitoring and early alerting systems for our production environments, and the steps we need to take to make sure our production tests don’t affect our users.