Sergio López
Lead Product EngineerTelecommunications Engineer
Hi, I'm Sergio López
Lead Product Engineer · Telecommunications Engineer
Ask me anything about Sergio.
Craft
I build and run platforms end to end: backend, web, mobile and cloud.
- SecurityCloud Armor, rate limits, dependency audits
- ObservabilityError tracking, logs and alerts
- ReliabilityZero downtime, autoscaling, PITR
- Infra as codeTerraform, several environments
Rails
React
Flutter
Google Cloud
GKE
Terraform
PostgreSQL
Granada, Spain
37.18° N · 3.60° W
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CET· remote
Foundation
Trained in networks, telematics and cybersecurity. That is where my focus on reliability and security comes from.
- EdgeCloud Armor (WAF) in front of everything
- NetworkPrivate VPC: nothing public that needn't be
- IdentityScoped identities, least privilege
- DataManaged secrets, backups with PITR
MEng
Telecommunications Engineering
2021 – 2023
Portfolio
Featured projects
Systems I designed, built and answer for in production.
PictoEscritura
Lead Product Engineer & Technical Owner
A platform that more than 200 schools use to teach writing with its own method. I joined as a full-stack developer and since late 2024 I'm the sole technical owner: I decide the architecture, build it, ship it and answer for it in production.
- 200+schools
- 50,000students
- 4platforms, one codebase
- 0downtime in the migration
- Web productRuby on Rails 8 API and React SPA for teachers and pupils: classes, activities, rubric-based assessment and story publishing.
- Cross-platform appsFlutter for iOS, Android, Windows and macOS from one codebase, through store reviews and updates to an installed base.
- Move to KubernetesFrom a managed PaaS to GKE Autopilot, all in Terraform: several environments, private networking, managed secrets. No downtime and ~45% lower projected monthly cost.
- Data & MLInfrastructure for the learning-analytics module (CDTI-funded R&D): nightly pipeline on Cloud Run Jobs and Workflows, time series in TimescaleDB.
- Operations & securityCI/CD, reproducible deployments, observability with Cloud Monitoring and Logging, Cloud Armor, private networking and least privilege.
- Built with AI agentsAI agents for code, QA, releases and support, with human sign-off on anything that touches production.
- Ruby on Rails
- React
- Flutter
- Google Cloud
- GKE
- Terraform
Cloud SQL · MySQL
Memorystore- TimescaleDB
Docker
Obol Studio
Founder · an automated business, run with AI end to end
A side project I run as an automated business. AI agents cover the whole cycle: they quote each product, write the proposal, design, build, test and deploy it, and plan and publish the social media campaigns. I bring the engineering: I designed the system, I set the quality bar and I review every delivery before it reaches a client. The aim is extra income from products held to the same standard as my full-stack work.
- LandingsWebsites that bring customers or validate an idea
- SaaSA working product, ready to sell
- AI agentsReal work, with limits and human review
- SystemsOwn systems and apps · coming soon
- Automated end to endAI agents quote each request, draft the proposal, write the code, test it and ship it; others plan and publish the marketing on social media. I designed the pipeline and sign off on each delivery.
- Local businesses and startupsWebsites with SEO, bookings and payments for local businesses; SaaS products and AI agents for startups. Fixed price and closed scope: the agents prepare the quote and I confirm it on a call.
- Lean infrastructureNuxt 4 rendered on Cloudflare Workers, requests stored in D1 and mail through Cloudflare; every push to main deploys itself.
Nuxt 4
Vue
TypeScript
Tailwind CSS
Cloudflare Workers · D1- AI agents
Squadwatch
Personal project · design and code
A local, read-only security auditor for the AI agents on a developer machine. It finds Claude Code, Cursor, Codex and seven more, reads their permissions, MCP servers, hooks and instruction files, and reports what each one can reach, what it exposes and how to fix it, without running any third-party code.
- 10AI agents supported
- 14security rules
- 0network connections
- Lethal trifecta, per projectFlags agents that combine private data, untrusted content and a way to send data out without confirmation, says in which project it happens and checks the guard hooks and sandboxes that stop it.
- Evidence for every findingFile and line, why it matters and what to change: secrets in plain text, wildcard shell rules, unpinned MCP servers, hooks others can edit, hidden Unicode in AGENTS.md.
- Private by designStatic scan, secrets always masked, no network calls. The dashboard is embedded in the binary and only answers on localhost.
Go
Linux · /proc
Dashboard in vanilla JS- MCP
- OWASP LLM Top 10
Freelance clients
Organisations I've built software for as a freelancer since 2018.
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Ruby on Rails · Vue
SoundMachine
Formerly The Sensory Lab: background music for shops and brands. Mainly backend work in Rails, with Vue and MongoDB: fixes, improvements and new features.
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Desktop app · Flutter
FEFF
Runs championships for the Spanish Fitness and Bodybuilding Federation (IFBB Spain) offline, over its own local network: weigh-ins, judges, scoring and results.
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Tourism apps · Flutter
Ayuntamiento de Torrox
Tourism apps for tablets in the town's museums, and a quiz game about its history: the Moriscos, the watchtowers, the sugar mills and the pirates.
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Augmented reality · RFID
Camino de Santiago
An app for pilgrims with augmented reality and RFID tags for the stamps on the pilgrim's passport.
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Flutter app
National Shrine of Our Lady of La Leche
The app for the shrine at Mission Nombre de Dios, in St. Augustine, Florida.
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STUARQ
iOS & Android app
Stuarq
Stuarq Gest, to manage architecture projects: built from scratch in Flutter with a Rails backend, and published on Google Play and the App Store.
Tech stack
My skills
Drag the sphere, or move your cursor over it.
AI & agents
AI agents doing real work, under human review.
Claude Code, subagents, skills, hooks and MCP. Each agent has a narrow role; anything that touches production goes through me.
Interfaces & apps
Usable, intuitive interfaces on any screen.
React and Vue on the web; Flutter for iOS, Android, Windows and macOS from one codebase, on the App Store and Google Play.
Backend
Clear, fast, well-tested APIs.
Ruby on Rails 8, Ruby and SQL. My own REST APIs, serving the web and the apps.
Cloud & DevOps
Reproducible, scalable infrastructure.
Google Cloud with Terraform: GKE, Cloud SQL, Cloud Run, Cloud CDN, Cloud Armor, Memorystore. Docker, Kubernetes, CI/CD, Linux, Git.
Databases
Sound data and fast queries.
PostgreSQL, MySQL, SQLite and TimescaleDB; Firestore and Cloud Functions; the ELK stack for analysis.
Security & networks
Security in layers, from the network to the data.
Network design and security, honeypots, ML-based attack detection and telematics.
Lead Product Engineer
Six pieces, one product.
Backend, interfaces, cloud, data, security and AI: my job is making every piece fit with the rest, and answering for the whole.
Let's build something.
Open to remote roles and freelance projects. If you need someone who can own a product from database to App Store, let's talk.
Email
LinkedIn
Phone
Location
Granada, Spain · Remote · Spanish (native) · English (B2)