Velja is a free and open source Mac app that helps users manage their browser preferences by automatically opening links in specific browsers or apps. It offers customizable options, such as choosing a default browser, setting apps to open in different browsers, and creating custom rules for specific URLs. The app also includes features like toggling "mailto" codes when copying email addresses and removing tracking codes from copied URLs. While it may not be available on iPhone, Opener is an alternative option that shares similar functionality at a lower cost.