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.
Rate limits, holidays and atomic writes in our market data layer
How we fetch daily prices for US and Indian stocks without tripping Yahoo’s limits, how we tell an NSE holiday from a missing file, and what we haven’t fixed.
5 October 2026 · 14 min read Algo tradingThe look-ahead bias our backtester prevents, and the leaks it misses
Our daily backtester shows its detectors only past bars and fills stops pessimistically. What still leaks in, and a checklist for building your own.
5 October 2026 · 15 min read Algo tradingOrder safety by default in code that can place trades
How 9io Alpha keeps order code safe with paper ports, dry runs, order caps and broker-side exits, and the cancel-then-sell race we still have to fix.
15 September 2026 · 14 min read Algo tradingGuarding an LLM research pipeline with two reviews and a judge
How 9io Alpha checks every model answer with two differently prompted reviews, a judge, rule-based checks and a fallback for when the model fails.
15 September 2026 · 13 min read