Fake user agent. Browser {Help needed}

It is possible to create a browser which user random user agent like firefox, chrome, safari.

And if we surf site on that browser then it will impossible to for site owners that we are using fake user agent. I mean they cant detect I am using fake user agent.

If yes then how can i do this..

Please share your tips about this.

Thanks In advance.

Firefox with User Agent Switcher extension will let you use literally any user agent you'd like. It should be pretty much undetectable as long as you're using a real user agent string from another browser, which I believe User Agent Switcher has built in.