“What do you do?” is a small-talk question and it is also, sneakily, a status question. Whoever asks is looking for a way to place you on the map of familiar occupations so they can decide how to talk to you. If your job is easy to name, no problem. If your job is not, the question becomes weirdly stressful.
What I have learned to do is answer the question underneath the question. When someone at a party asks what I do, they are usually not asking for a job title. They are asking “how do you spend your days?” or “what do you care about right now?” or “how do we relate to each other for the next four minutes?” If you answer with the literal job title, you have accepted a small, shallow version of the conversation. If you answer with something specific about the actual texture of your week, you have offered a real conversation.
My answer now is usually “I build things on the internet, most of them boring but a couple I am proud of.” That opens a door to specificity. About half the time, the person asks a follow up. About half the time, they nod politely and move on. That is fine. The half that follows up are the conversations worth having, and my old answer — “I’m a software engineer” — used to give people permission to disengage before they got there.