I want to do that. Not necessarily travel, but just to do good in the world. A complicated question in and of itself is what can you do to improve situation in the world? What problem do you feel most interested in solving? That will determine where and how you should look for opportunities. If there's no currently existing opportunities, you can make one yourself - be "self-employed", which would be a big challenge.
There's many avenues, though. Non-profits always need web developers and other programmers. You can try working in public sector. If travelling is something you seriously consider, it would require a lot of preparation.
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