Hello there!

I'm Fernando Putallaz, aka FeRHeDio, I'm an iOS Developer from Argentina.

I've been building iOS apps since 2018: some small startup products, some that never saw the light, and some inside big teams behind apps with tens of millions of users.

These days I work in two ways: directly with a handful of founders and product teams, and by shipping my own apps on the App Store.

What I've been most into lately is on-device AI: running models right on the iPhone instead of calling a cloud API. No per-token bill, and your documents and the AI inference stay on the device. I got deep enough into it that I shipped WhattaRAG, a small app that does full retrieval-augmented generation (RAG) entirely on the device, in 100% native Swift, at 4.4 MB. It's on the App Store if you want to poke at it.

Building WhattaRAG has taught me a lot of AI engineering, and I'm enjoying that side of the work a lot. I wrote the whole pipeline myself: chunking, hybrid keyword and vector search, ranking, the prompt. Then I built an eval suite to find out what actually works: a golden dataset of 242 test cases, a held-out set, retrieval metrics, hallucination tracking. I wrote up what that eval suite taught me if you want the details.

Over the years I've worked across Swift, Objective-C, UIKit, SwiftUI, Combine, Apple's Foundation Models, and more recently RAG and LLM evals. What really matters isn't which technology gets used, it's building something of meaning, in the best case changing people's lives.

How I like to work

I treat code as a communication tool, and I care about clean code and SOLID principles where they actually help. Put simply, I value simplicity over cleverness, clear ownership over diffused responsibility, and sustainable progress over short-term velocity.

I've always liked test-first work, and evals are how I bring that to AI: if I can't measure a change, I don't claim it.

If you'd like me to help with your project or want to learn more about me, feel free to reach out via email at contact@altocodelabs.com, connect with me on LinkedIn, or find me on X. You can also see how I work at altocodelabs.com.

Thank you!