CircleCI has integrated with Sauce Labs to enable secure cross-browser front-end testing on the cloud. This integration allows developers to run tests easily, without needing extensive configuration, and ensures that their applications work across various platforms and versions. With CircleCI's Continuous Integration service, developers can automate their testing process, and if needed, execute tests locally in a build container using Sauce Connect, a secure tunneling utility. The integration provides a hassle-free experience for developers, allowing them to focus on creating great software without managing the costs and hassles of supporting multiple systems and grids.