Who is using AI to code?
Global diffusion and impact of generative AI
Simone Daniotti, Johannes Wachs, Xiangnan Feng, and Frank Neffke
Science – 22 Jan 2026 – First Release
Abstract
Generative coding tools promise big productivity gains, but uneven uptake could widen skill and income gaps. We train a neural classifier to spot AI-generated Python functions in over 30 million GitHub commits by 160,097 software developers, tracking how fast, and where, these tools take hold. Currently AI writes an estimated 29% of Python functions in the US, a shrinking lead over other countries. We estimate quarterly output, measured in online code contributions, consequently increased by 3.6%.AI seems to benefit experienced, senior-level developers: they increased productivity and more readily expanded into new domains of software development. In contrast, early-career developers showed no significant benefits from AI adoption. This may widen skill gaps and reshape future career ladders in software development.