Computer programmers can work from their computers. If your main job is working from your computer, you can work from anywhere in the world. All you need is access to a computer and the internet. Working from home has become a new thing for many people. Being a digital nomad has made everything easier.
As a backpacker, you will have opportunities to work at hostels. Many hostels look for people to work. These can be temporary jobs or even seasonal in which you help clean, work the desk, or help take care of the guests.