Defects are cheaper to fix when they're caught early. That's why we always try to get the fastest possible feedback to developers in the form of static analysis, unit tests or end-to-end tests run in the local environment. Accessibility is no exception to this and that’s why we've featured tools such as Lighthouse, axe-core and axe Linter in the past. When it comes to automatically testing web pages that are already deployed in production, one of our teams chose instead to go with IBM Equal Access Accessibility Checker in a head-to-head comparison. Although we're still in the process of assessing the results, we can say that it offers an efficient way to test pages once they've been deployed. We emphasize that this should be used to augment, not replace, early automated testing by the developer. The tool is distributed under a Creative Commons license and is free to use under those restrictions.