Blog
Engineering notes from 9io.
How we build products, AI systems and trading infrastructure — and what we learn on the way. Written by the people who do the work, with the sources linked.
Infrastructure
Three Amplify Hosting limits our Next.js BFF only hit in production
A 6 MB response cap, an 8 KB URL limit and a localhost origin broke parts of our Next.js BFF on AWS Amplify. What we saw, the fixes, and how to test early.
7 October 2026 · 11 min read Next.jsHow redux-persist’s PersistGate emptied our Next.js server HTML
Our public Next.js pages returned 200 with full head tags, but each body was a 1 KB loading screen. Why PersistGate did it, the fix, and how to check yours.
26 September 2026 · 7 min read Web performanceCaching server-rendered Next.js HTML at the edge, by device type
We cached a Next.js storefront’s HTML on Cloudflare, split by device type. Cached pages come back in about 70 ms; mobile PageSpeed rose from 65 to 87.
8 September 2026 · 16 min read