Does the job well and the best random user agent switcher I found so far. Consider adding Chrome for Android so that there can be a few versions (latest and some early versions of chrome for mobile) of that user agent, the more the better. Consider keeping the user agents updated and more randomized from time to time so that websites do not blacklist certain user-agents. Overall I see great potential in your add on and hope you keep it updated for a long time and keep it growing with functions.