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Diogo Seca
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Fractional CTO · Porto, Portugal

Fractional CTO for AI-built products. From prototype to production.

Your product works in a demo. Then a customer hits a bug, a deploy breaks sign-up, or the team loses hours to manual work around it. I take AI-built prototypes and early products to production, and automate the repetitive operations around them. Fixed scope, tested, shipped.

Tell me about your project How I can help
Diogo Seca, smiling, in a warmly lit room
Diogo Seca Porto

Current CTO role

Now

Charging schedules for commercial electric van fleets, so every van is ready for its shift without going over the depot's power limit.

I own the optimisation, the live vehicle data, and the infrastructure underneath.

CTO · fleet charging optimisation SaaS
MTWTFSS

A seven-day plan · illustration

Local timePorto

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Porto, PortugalSame time zone as London

Konetik

Acquired 2023

Machine learning on real vehicle usage data that told companies which of their vehicles could go electric, automating manual consulting work so it could sell at scale. Quartix PLC acquired the company in 2023, and I led the technical handover.

Backend & ML

BJJ Graph

Live

An interactive map of Brazilian Jiu-Jitsu positions and the moves between them. The source code is public.

bjjgraph.org

Not Investment Advice

Live

A parody investing blog written entirely by a language model, built in a couple of days as an experiment.

notinvestmentadvice.ai

Selected writing

  • Lovable SEO: what still keeps your app out of Google and ChatGPTNov 2026 · 8 min
  • Based AphorismsOct 2026 · 5-part series
  • 12x Developer: Using the 1% Compound Rule to Grow 1100%Dec 2025 · 14 min
  • Are you still diversifying using the Markowitz model? Welcome to the 21st century.Jul 2020 · 7 min
  • How to Export your Jupyter Notebook to Medium in 3 easy stepsJul 2020 · 1 min
Browse all 9 articles
About

Fractional CTO and machine learning engineer, based in Porto.

I started out writing trading algorithms for clients, then did machine learning research at INESC TEC, mostly on time series, and published four papers. At Konetik I built the machine learning that told companies which of their vehicles could go electric; Quartix PLC acquired the company in 2023 and I led the technical handover. I built HowRisky.ai end to end on my own. I'm now CTO of a SaaS that plans charging for commercial electric van fleets. As a fractional CTO I take on a small number of engagements each quarter, so each client gets senior attention.

Contact

Have a prototype your customers are starting to rely on?

[email protected]

Send a link, a repo, or a few lines about what you need. I reply within two working days.

Explore services and pricing

On the bench

Paused
  • HowRisky.aiRetirement risk estimates using Monte Carlo simulation. Built end to end on my own.
  • FutureGiftAn ETF position as a gift, held for a child until they turn 18.

Papers

INESC TEC
  • Benchmark of Encoders of Nominal Features for RegressionWorldCIST 2021 · peer-reviewed
  • Estimating the Likelihood of Financial Behaviours Using Nearest NeighborsComputational Economics 2023 · peer-reviewed
  • Hierarchical Qualitative ClusteringarXiv 2020 · preprint
  • A Review on Oracle Issues in Machine LearningarXiv 2021 · preprint
© 2026 Diogo Seca · Porto, Portugal
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Set in Hanken Grotesk and IBM Plex Mono

Work with me

From prototype to production.

I take AI-built prototypes and early products to production, and automate the repetitive operations around them, so bugs, broken deploys and manual work stop costing you customers and hours. Fixed scope, tested, shipped.

  1. 01You have a working prototype, built with AI or by hand, and need it ready for real users.
  2. 02You need a new website or web app, with a clear scope and someone to build it.
  3. 03You need someone senior to make architecture and budget calls a few days a month, without a full-time CTO.

Built with AI? You can keep using it. Keep asking Lovable, Claude Code, Codex or Cursor for changes. I set up tests, review and deployment checks so you have a reliable process for getting those changes to users.

Four ways to start

Production Readiness Audit

From €800

Scaled to the codebase

What will break before real customers find it: a prioritised risk list, a remediation plan and a recorded walkthrough.

3 working days for one small codebase; larger codebases quoted up front. Diagnosis and plan, not the fixes.

Website Modernisation

From €1,800

Two to three weeks

Your site rebuilt around the enquiry you actually want, with analytics set up so you can see whether it worked.

Around five pages, lead capture, basic SEO, handover.

Ship It

€1,200 to €2,000

One week

Git version control, automated tests and a CI/CD pipeline, so you can deploy reliably and roll back if needed. Includes a runbook the next engineer can follow.

One repository, one environment.

Fractional CTO

From €2,000 / mo

Ongoing, monthly

Architecture, budget and vendor decisions, and code review, with a weekly call. I write code myself when that's faster.

Build work beyond small fixes is scoped separately.

Every engagement includes a weekly call and a written update. You won't have to chase me to find out where things are. I take on a small number of engagements each quarter, so each client gets senior attention.

How I work

I run AI coding agents in parallel on well-defined tasks. I make the architecture decisions, review and integrate everything, and I'm responsible for the result. Tests and CI come first, so that working fast doesn't mean things break the following week. I always use the newest, most capable AI models available, because they write better code and make fewer mistakes. Their cost is included in the price.

Previous work

  • BJJ GraphAn interactive map of Brazilian Jiu-Jitsu positions. React, Cloudflare, Supabase, Playwright. Live, and the source code is public.
  • KonetikBuilt the machine learning on real vehicle usage data that told companies which of their vehicles could go electric, automating manual consulting work so it could sell at scale. Quartix PLC acquired the company in 2023, and I led the technical handover.
  • Current CTO roleCTO of a SaaS that plans charging for commercial electric van fleets, so every van leaves the depot charged without going over the depot's power limit. I own the optimisation, the live vehicle data, and the infrastructure underneath, and I take customers from pilot to production.
  • HowRisky.aiBuilt end to end on my own: the modelling, the backend, the frontend, the infrastructure and the go-to-market. Paused.
  • INESC TECMachine learning research, mostly on time series. Four papers.

Tell me what you're working on.

A repo, a link, or a few lines about the problem. I reply within two working days, with a fixed-price scope if it's a fit, or a short note if it isn't.

[email protected]

Invoiced by a Portuguese company with an EU VAT number registered in VIES. Company details come with the quote. Prices exclude VAT. Clients in Portugal pay VAT at 23%. Businesses elsewhere in the EU are invoiced under the reverse charge, and clients outside the EU are invoiced without Portuguese VAT.

Replies within two working days

Send me a project