Senior Software Engineer

Carlos Marin

10+ years building web applications.

Good software is built by good engineers. Great software is built by great teams.

About me

I’m a Senior Software Engineer with 10+ years building modern web applications. I care deeply about building good software - and building it with good people.

I combine technical depth with pragmatism: understanding problems properly, making thoughtful architectural decisions, and finding the balance between doing things right and getting things done. I work mainly with React and JavaScript/TypeScript, building scalable frontend architectures and clean interfaces, as well as full-stack (Node.js) solutions and broader architecture.

I focus on software that is simple, measurable and maintainable, prioritising clarity and long-term efficiency. I enjoy the parts of engineering beyond writing code: system design, performance, solid APIs, developer experience, engineering standards, and technical decision-making. I’m currently exploring how to integrate AI into development workflows.

I also care deeply about the human side of engineering. I enjoy mentoring, pairing, challenging ideas, and helping teams grow stronger - both technically and as a group. I value empathy and fostering environments of continuous, shared learning.

Build better software. Make better decisions. Leave the team stronger.

Stack

HTML
CSS
TypeScript
React
Next.js
Node.js

Portfolio

WordsFrame

In production · 50+ orders

Personalized poster e-commerce - designed, built and run end to end

WordsFrame turns up to 10 words into a custom Scrabble-style crossword poster, fully customizable with layouts, colours, fonts and text. Available as digital downloads, prints, framed posters and merch (mugs, tote bags), with worldwide print-on-demand fulfillment.

  • Next.js 16 / React 19 / TypeScript frontend, styled with Tailwind CSS 4
  • Stripe checkout with webhook-driven fulfillment; Supabase (Postgres) for orders, coupons and subscribers
  • On-demand poster image rendering on AWS Lambda with headless Chromium (Puppeteer), stored on S3
  • Print-on-demand via Gelato; transactional and scheduled upsell emails with Resend
  • AI support chat powered by Claude; error monitoring with Sentry and Umami analytics
  • Tested with Jest + React Testing Library and Playwright E2E; CI/CD and deployed on Vercel

Experience

Insendi

Jun 2021 - Present

Team Lead and Senior Software Engineer

  • Contributed to raising engineering standards, focusing on code quality, maintainability, and sustainable development
  • Led major technical initiatives across the stack, from Next.js/TypeScript frontend architecture to Express (Node.js) backend services
  • Drove refactoring and migration initiatives, reducing technical debt and system complexity through pragmatic architectural decisions
  • Improved development workflows, testing strategies, CI/CD processes, and developer experience
  • Took ownership of complex technical problems, working closely with product and design to deliver robust solutions
  • Championed testing and accessibility, driving the adoption of React Testing Library (RTL) and automated accessibility testing with axe
  • Acted as a technical reference within the team, mentoring engineers, pairing on complex problems, and sharing knowledge

Apploading

Feb 2017 - Jun 2021

Junior Software Engineer to Senior Software Engineer

  • Started as an intern to finish my university degree and progressed to a senior position
  • Gradually took on responsibilities: requirements gathering, analysis, and team-based project development without supervision
  • Product and architecture decision-making
  • Meeting directly with clients to gather their requirements and needs

Publications

Multimodal human-machine interface devices in the cloud

2017

Springer

Proposes a paradigm where any input device connects to web applications through a single shared interface, freeing developers and users from depending on specific physical peripherals. Devices are registered on an interface server and communicate over a network of WebSocket modules under a scalable SOA architecture. Aimed beyond gaming - interactive teaching, accessibility and adapting web apps for non-technical users.

Multi-user web game based on the Internet of Interfaces (I-o-I)

2017

CDVE 2017 - 14th International Conference on Cooperative Design, Visualization and Engineering, Springer

A case study building a Pong-inspired web game on the Internet of Interfaces (I-o-I) architecture developed at UIB. It relies on virtual interfaces so a variable number of users can join and interact in different ways. Demonstrates I-o-I as a flexible, multi-user approach to real-time web interaction.

Education

UIB - University of the Balearic Islands

2012 - 2017

Computer Engineering with a specialization in Information and Communication Technologies.