Put a website in maintenance mode?

Question

I\'ve developed my first web application which, surprisingly, is getting very popular.

Because the website is now live, I have a hard time doing some changes, in fe

Answer 1

I wish to avoid having a duplicated instance of the web application for testing.

That's your problem right there. For anything but the most trivial sites, you should have a staging or development instance. You should be using source control and have a script to update the main instance.