Introduction The Generative AI tooling ecosystem has exploded over the past two years. What started as a handful of Python libraries has grown into a rich, opinionated landscape of frameworks spanning multiple languages, deployment targets, and philosophy bets. As a developer who has shipped production applications using all five of the frameworks covered in this article, Genkit , Vercel AI SDK , Mastra , LangChain , and Google ADK , I want to offer a practical, hands-on view of where each one excels, where each one falls short, and what I would reach for depending on the project I'm building. This is not a benchmark post. Tokens per second and latency numbers go stale within weeks. Instead, this is a developer experience and architecture comparison, the kind of thing that matters when you're deciding what framework will carry your product through 2026 and beyond. A quick note on scope: all five frameworks are in active development and moving fast. Code samples in this article use the APIs as of April 2026 .…