About

Hi, I’m Simon.

I’m a backend engineer and tech lead based in Cantabria, Spain. I’ve spent 17 years building systems that real people depend on, and a few of them making the hard calls as a founder.

What I’ve done

• Co-founded a B2B SaaS (Stomio, 2021–2024). I built the platform from the MVP (Node.js, PostgreSQL, Redis, Vue), integrated it with Okta, Jira and Slack, and took it through SOC 2 compliance with yearly penetration tests. Later I hired and led the engineering team while still coding.
• Worked on CARTO’s core APIs (2017–2021). A maps tiler and a SQL API receiving millions of requests a day. In a team of two or three, we rebuilt most of the code while keeping it running and fast.
• Today I’m a tech lead at a global scale-up, where I ship LLM-powered features to production: document extraction, AI triage agents and the workflows around them.
• Before that, backends for consumer apps with millions of users, and the first backend of an insurtech startup.

Why I do this

I’m a builder. What I love most is starting things from scratch: the first commit, the first users, the first time something breaks in production and you work out why. Working with founders who are building their own thing keeps me close to that. It keeps me feeling young, fresh and energized.

I’ve also been the founder who had to decide whether to rewrite the product while customers were waiting. The difference between a good and a bad answer was months of work and a lot of money. Founders with an AI-built app face the same decision earlier and with less help, and most of the advice they get comes from someone who sells only one of the answers.

AI builders are a great way to get to your first users. I’m not here to tell you that you did it wrong. I’m here to help you keep what works and fix what will hurt you.

How I work

• I work with only one or two clients at a time, so each one gets my full attention.
• Mostly async, in English or Spanish. Calls in the European evening (US East Coast midday).
• Fixed prices for defined work, written proposals, and you own all the code.
• No referral fees from platforms or tools, so my recommendations are only about your app.

Elsewhere: X ·my old blog