Beltrán Rengifo — Product Engineer · Madrid
I build products end to end, with UX and UI at heart.
A product engineer with 14 years building web products end to end — APIs and data, CI/CD and deployment, and the interface on top. Fluent across the stack, from Node, Java and Python to Postgres, with a particular eye for UI and UX.
Based in Madrid, remote or hybrid.
Experience
Dec 2022 — Jul 2026
Squad Lead — Experience team
Feb 2026 — Jul 2026
Led a cross-functional squad responsible for the user experience across all Mews products. We took over the shells of every product, unifying and standardising them, along with the Dashboard of the main application, the PMS, and parts of the Smart Assistant Search engine. Designed and built the app switcher for the whole Mews ecosystem, end to end. Also took on backend maintenance over assets and translations. Planned the work and mentored junior engineers.
Tech Lead — Mews Design System, Platform team↗
Jun 2024 — Feb 2026
On top of my senior engineer role, I took on the technical lead of the Mews Design System, as formal code owner of its libraries: the legacy library and the new implementations for both B2B and B2C. Among many other initiatives, I was responsible for, and the main contributor to, the work that followed an independent accessibility audit of Mews's guest-facing products against WCAG 2.1 AA and the European Accessibility Act — with the design system as one of its largest areas. Beyond that, I worked on large, key new components such as the DataGrid, built on TanStack Table and taken a long way past it: client-side, server-side and tree variants behind one API, and many user-facing features.
Senior Software Engineer — Mews Design System, Platform team
Dec 2022 — Jun 2024
Shipped component libraries and frontend tooling for a large React/TypeScript monorepo, as the main contributor on my team and one of the top contributors to the whole repository. Likewise one of the main contributors to the multi-brand design-tokens pipeline (Figma → Token Studio → Style Dictionary), where one source of truth drives four themes across two brands on web and Android.
Jun 2021 — Dec 2022
Senior Software Engineer, Product
Product engineer on the Tango team, working in Java and React through Liferay's portlets. I worked mostly on the Content Dashboard — audit charts, the item info panel, previews, versions, sharing and subscriptions — and on the Frontend Data Set, the tables shared across the platform; besides, prioritised segment variations for Collections, down to the Service Builder layer, and the Page Audit built on Google PageSpeed.
Jan 2021 — Jun 2021
Frontend Lead, Product
Led the frontend of a telemedicine platform, taking its Vue codebase to the next level — component reusability, best practices, and large-scale refactors, including introducing an app-wide shared store as the single source of truth for application state. Reviewed architecture, standardised code reviews, fostered a strong team culture, and improved the existing design system across Vue, TS and SCSS.
Sep 2018 — Jan 2021
Product Owner & Engineer — Onesait platform website↗
Jan 2020 — Jan 2021
Owned and delivered the main web app promoting Onesait products, bridging engineering and marketing. Led a team of four engineers and one designer, managing multiple stakeholders.
Senior Software Engineer & Consultant — Onesait Design System↗
Sep 2018 — Jan 2020
Main delivery engineer on the Vue.js-based design system, and the go-to reference supporting every product engineering team adopting it.
Jan 2018 — 2019
Web Development Instructor
Taught intensive full-stack web development bootcamps. Fast-paced and hands-on — and nothing hones your own fundamentals quite like teaching them to others.
Feb 2015 — Jan 2018
Web Development Lead
Led a team of up to six developers at a design-led agency — client-facing work, pitching, and mentoring juniors — delivering marketing and corporate sites, e-commerce stores, and a steady stream of microsites for clients like Edelvives, ECAM, Universidad Autónoma, Mapfre and Telefónica. In a studio that lived and breathed design, the bar was pixel-perfect: high-craft UI, rich interactions, and truly responsive layouts, on jQuery, Bootstrap, PHP and WordPress, with Less and Sass built on Node, and our first steps in Angular.
2012 — 2015
Web Developer & Instructor
Helped build and maintain the company's main site and the client websites delivered by its agency arm — my first taste of agency work and shipping custom WordPress in PHP. Doubled as the in-house WordPress instructor, teaching plugins, themes, styling and the PHP basics that make it all tick — and learning plenty the honest way myself.
2002 — 2015
A previous life
Film & TV Sound Engineer↗
Before software, sound for film and TV, from 2002: location sound, post-production and mixing. Post-production and music recording on En la cuna del aire and sound design on Flores de Ruanda, both Goya winners for Best Documentary Short; location sound and post on About Ndugu, shot in Kenya and premiered at the Berlinale. With my friend Iván I founded lacasaestudio, still going.
Selected work
A rehearsal tool for bands: stems, MIDI and an editable chord chart from any recording, on a self-hosted audio-ML pipeline. In private beta.
Next.js 16 · React 19 · Supabase · Tone.js · wavesurfer · Python — Demucs, Basic Pitch, Omnizart · TensorFlow · PyTorch · Docker on Coolify (self-hosted)
Read the case studyRewrites plain Spanish in the voice of a cycling commentator — a RAG pipeline in Python, with FastAPI, pgvector and Claude.
Python 3.14 · FastAPI · Claude API · pgvector on Supabase · Hugging Face inference · React 19 · Vite · whisper.cpp · Vercel
Read the case studyA Mapbox map of Carabanchel's cultural landmarks in Madrid, built with IED (Instituto Europeo de Diseño) — a Strapi back office with the business logic in its lifecycle hooks and services.
React · Redux + sagas · Mapbox GL · Leaflet · Strapi · MongoDB
Read the case studyA paella calculator and cooking assistant: broth, fat and salt from the rice, the cooking time and each pan's measured evaporation, plus a retrieval-backed assistant — as an installable PWA.
Astro 5 · React 19 · Supabase · Groq — Llama 3.3 70B · Hugging Face embeddings · Framer Motion · Radix · PWA · Vercel
Read the case studyCapabilities
Fluent across the stack, from the database to the interface, with a particular eye for UI and UX — and AI a natural part of how I build today.
Backend & data
- Node.js · REST APIs
- Java · Liferay
- Python · FastAPI
- Postgres · Supabase · pgvector
- Strapi · MongoDB
- PHP · WordPress
Frontend · UX/UI
- JavaScript · TypeScript
- React · Next.js
- Vue · Nuxt · Astro
- HTML · CSS · Sass · Less
- Design systems · tokens
- Performance · Accessibility
Infrastructure & delivery
- Git · GitHub Actions · CI/CD
- Docker · Coolify · Hetzner
- Vercel · Netlify
- Vitest · Playwright · Testing Library
Practice
- Code review · standards
- Mentoring
- Tech & squad leadership
- Agile · Product ownership
- AI workflows · automation
How I work with AI
A snapshot of the tools I use every day, how I work with them, and what I have built on top.
In use as of October 2026
Tools & models
- Claude Code, my main environment
- Claude Code plugins: Superpowers (brainstorm, plan, TDD), Frontend Design, Vercel
- Claude Opus day to day; Sonnet and Haiku in my projects, by cost
- Codex and ChatGPT for a second opinion
- Supabase and its MCP, used heavily
- Fluid Voice to talk to the agents
- Claude in Chrome to test in a real browser
- Local models: whisper.cpp, Hugging Face embeddings
How I work
- Agents from idea to pull request: spec, plan, implementation
- Review by subagents before anything merges
- Issues built for agents, with beads
- MCP connectors: Gmail, Calendar, Drive, Dropbox, Vercel, the browser
- Caveman and RTK to keep token use lean
- My own skills on the Anthropic API for Jira, team work and Scrum ceremonies, and my own Claude Code hooks; one branch and one pull request per change, whoever writes the code
Built by me
- Radio Perico — a RAG pipeline in Python over a corpus of my own
- Ensayadero.studio — in-house audio ML for stems, MIDI and chords, no paid APIs
- PaellaLab — a cooking assistant with semantic search and Llama 3.3 70B on Groq
- agent-voice — Claude Code that speaks
- worktree-flow
- Assisted Review — grading submissions with Claude, in progress