SergioPeñaBayona

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Exploded drawing of a web product: design, frontend, backend, data and deployment as five stacked layers.
Fig. 01 — One product in five layers, drawn apart at the joins.
  1. Design
  2. Frontend
  3. Backend
  4. Data
  5. Deploy

Full-stack product engineerRemote from Spain · Freelance and full-time

I take a product from the brief to production: design, frontend, backend, data and deploy, as one engineer, remotely from Spain. Open to freelance projects and full-time roles.

How I work

One engineer,five layers.

Every product I ship passes through the same five layers. Most teams split them across people and hand the work over at each join. I keep them in one pair of hands, so nothing is lost in the handover.

  1. 01

    Design

    Screens and flows before code, designed in the browser with real content. What you approve is what ships.

    a clickable prototype

  2. 02

    Frontend

    Fast, accessible interfaces: semantic HTML, careful CSS, and JavaScript only where it earns its place.

    the product, in the browser

  3. 03

    Backend

    APIs, authentication and business logic, typed end to end and tested where it matters.

    an API you can rely on

  4. 04

    Data

    The model, the schema and the migrations. Boring, reliable storage over clever.

    a schema that lasts

  5. 05

    Deploy

    Hosting, CI and monitoring. A URL from day one and a release process that holds.

    a product in production

Work

Side projectsand clients.

What I have shipped, end to end. Each entry is a product in production: what it does, and what it is built with.

  1. 01

    Vrandalismo

    Client · Vrandalismo Studio, Madrid · 2026, ongoing

    Landing, case studies and a small store for a creative studio, in Spanish and English. A static Astro site with Sanity as the CMS: the studio edits every text in an embedded Studio, a build step generates both language dictionaries and fails if they drift apart. A Node API of about 250 lines turns the cart into a Stripe Checkout session. One VPS behind Caddy, deployed atomically from GitHub Actions every time the studio publishes.

    Astro · TypeScript · Tailwind · Sanity · Stripe · Node · Caddy · GitHub Actions

    Live site

Freelanceor full-time.

Remote, from Spain, with founders, agencies and product teams. If you need one engineer to take the whole product from the brief to production, write to me.

Write on LinkedIn See the code