Search for "Next.js AI chat" in 2026 and Vercel AI SDK still comes up as the de facto standard. Nothing wrong with it, but relying on the SDK means you often don't understand what's happening under the hood — how streaming actually works, what the Route Handler is doing behind the scenes.
I built this from scratch in a sandbox using only the Anthropic SDK. The entire flow: create-next-app, adding @anthropic-ai/sdk, implementing the Route Handler. It turned out simpler than I expected. About 50 lines gets you a production-deployable streaming chat backend.
One thing I noticed while doing this: create-next-app@latest now installs Next.js 16. Most tutorials you'll find are still targeting Next.js 14 or 15. This post reflects what you actually get in May 2026.
What We're Building
The app structure:
