Freelance software engineer in Barcelona, for projects on AWS.
I’m Joan Sanfeliu Vilarrasa, a freelance software engineer in Barcelona, and I take on custom software projects on AWS for companies that already run their own systems. At a fixed price per feature and with the code in your name.
- Sant Feliu de Codines · Barcelona
- Ten years of engineering
- Catalan, Spanish and English
01Projects
The projects I take on.
The companies I work with already have systems in place: an ERP, a CRM, an online shop or the usual spreadsheets. I build the missing piece and leave it running on AWS. Four kinds of project, each with work already delivered:
- 01
Applications, portals and APIs
An internal tool, a portal where customers or suppliers serve themselves, or the API that connects what you already have. For Malapell, online business orders with their own admin panel.
- 02
ERP and CRM integrations
So that data moves from one system to another on its own. For Binari, a .NET ETL connecting their clients’ ERPs to the warehouse, with AI-assisted client onboarding.
- 03
Automation, and AI where it saves hours
AI comes in where it actually helps, not everywhere. For Bloome, an MCP server over their backend so clinical staff can query without opening the interface; for SUMAL, a custom MCP connected to their WooCommerce catalogue.
- 04
Websites and AWS migrations
Habitabio’s real-estate website, in Next.js, AWS migration included.
02How I work
Three rules and six steps.
- 1
Fixed price per feature, never by the hour.
- 2
The first conversation is free.
- 3
If I cannot help you, I tell you on that same call.
The process
The full process, at SANFELIU- 01FitA call or a visit: what is going wrong, what you already have and what must not change.
- 02PrototypeA working demo with your own data, within one to three days and before any talk of price.
- 03ProposalA document with screenshots of your demo and a fixed price per feature.
- 04ProjectIn short phases, over weeks, with a real delivery at the end of each one.
- 05HandoverA handover record, the code in your name and the first month of minor changes included.
- 06ContinuityA support plan with no lock-in, or none.
03Who I am
Ten years of engineering and three products of my own in production.
I have ten years of engineering experience. Among other places, I have worked at NTT Data (2021–2023) and at MONEI (2023–2026), a payments platform. Since 2026 I have been full-time on SANFELIU.
I spend half my time building my own software, in production on AWS (today, taula.ai, Guestproof and Canasta), which I pay for and fix myself when it breaks. The other half, inside small and mid-sized companies that already run their own software and need someone who really understands it.
I work with TypeScript, Node.js, React and serverless AWS. I held the AWS Solutions Architect Associate and Cloud Practitioner certifications (2022–2025); both expired in December 2025. And, since 2023, I have taught frontend development at TecnoCampus in Mataró.
04Vacation rentals
Also software for vacation rentals.
It is a sector I have already worked in. Guestproof is one of my products in production, for vacation rental agencies: it publishes a review website under the agency’s own brand, built from the reviews of its properties on the booking portals. It grew out of the verified-review portal I built in 2026 for RentAllorca, a vacation rental agency in Mallorca; that portal is no longer online.
For RentAllorca I also built an AI agent to watch competitor pricing. And, in tourism, I built the four-language website of a group of three hotels in Cerdanya and Porto.
And an owner portal?
For a company that manages tourist apartments, it is one of the projects I take on: a custom web application where each owner signs in and finds the bookings and the occupancy calendar of their property, the statements, the invoices and the documents, connected, if your property management system (PMS) or channel manager allows it, to the data you already have. It would be the same kind of work as Malapell’s online business orders with their own admin panel. It starts like any other project: a call and, before any talk of price, a demo with your own data.
05Questions
Before you hire a freelancer.
Are you a company or a freelance developer?
I am self-employed. SANFELIU is the trade name I work under: I sign invoices and contracts myself, as Joan Sanfeliu Vilarrasa.
How much does a project cost? Do you bill by the hour?
I take on new projects at a fixed price per feature: you see it in the proposal, after a first conversation that is free and a demo with your own data.
Where are you based, and which languages do you work in?
I am based in Sant Feliu de Codines (Barcelona) and work remotely; the first conversation can be a call or a visit. I work in Catalan, Spanish and English.
Who owns the code, and what happens after handover?
The code is handed over in your name, with a handover record and the first month of minor changes included. After that, if you want it, a monthly plan with no minimum term: hosting on AWS, monitoring, backups, security and each month’s changes.
Do you use artificial intelligence in your projects?
Only where it saves hours. Sometimes you need real AI, and then I build it; sometimes connecting two tools you already have is enough; and sometimes the right thing is to tell you that you do not need it.
Let’s talk about your project.
The first conversation is free. If I cannot help you, I tell you on that same call.