Custom applications, built for your process
SANFELIU builds custom applications for companies in Barcelona and the Vallès: internal tools, customer and supplier portals and process tools that don’t exist yet, on AWS and with the code in your name. When nobody sells what you need, it gets built, with AI where it saves hours.
Updated
Fifteen minutes, free and with no obligation, with the engineer who would lead the project.
- TypeScript
- React
- Node
- .NET
- AWS serverless
- Claude
What we do
Internal applications
What you now do with three spreadsheets and an email. A tool that does exactly your process and nothing else.
Customer and supplier portals
Customers look things up, place requests and download on their own, and the AI answers what a person used to answer.
Process tools with AI built in
Classifying, extracting, drafting, deciding: AI as one piece of the workflow, with a person approving where needed.
Digital products
If what you want to build is a product to sell, that too. SANFELIU has two in production.
What it looks like in practice
The CRM we run our own clients on
A custom client-server application we use every day. It solves one specific thing: no contact that comes in through our websites gets lost, and every follow-up has a date.
- In the browser
The panel: contacts, companies, opportunities by stage, projects with their hours and each client’s documents, and cookie-free website traffic.
- On the server
An API on AWS that receives the website forms and saves them as new contacts. Every morning it flags the follow-ups that are overdue.
- With AI
An MCP connector so Claude can search it, log calls and move opportunities, with the same permissions we have.
A real example, day by day
A delicatessen in Sabadell wanted companies to build their Christmas hampers on the website, and to accept the orders from a panel. From first contact to production: eight days.
- 8 September
Fit call. They explain the case: company hamper orders come in by phone and WhatsApp, and in December someone has to call each company to confirm them.
- 8 September, evening
Prototype. A demo deployed at a private address, with their products: the hamper builder, the order panel and PDF documents that are generated on their own.
- 9 September
Prototype. The 3D box with their products and the campaign page.
- 10 September
Proposal. The fixed price, with screenshots of their demo, the scope, the timeline and the ongoing plans.
- 15 September
Acceptance. They try the demo with their own email and say yes. The same day, invoices and stock control go in.
- 16 September
Production. Live on their own domain. The changes they ask for when they see it go in the same day.
- Since then
Ongoing. The improvements that come from using it: two boxes with their logo, delivery dates based on the workshop’s capacity, the catalogue loaded from their spreadsheet, ready-made hampers and the shop’s own photos.
It’s path A in How we work: a prototype before the price, a fixed-price proposal and, if they want one, a continuity plan for campaign months only. How we work
The documents you receive
Both in the same format as the real ones, made with a project of ours: this website. Where an amount would go, it says X.
Evolve Cars: from WordPress to their own tool
- Evolve Cars imports and sells inspected cars from all over Europe, from El Prat de Llobregat. They had a WordPress site; now they have a website and a panel built for the way they work.
- They upload each car in the panel, and AI drafts the listing from the make, model and year, and translates it.
- The website, in Catalan, Spanish and English, with the stock, each car’s listing and made-to-order imports.
- In production since 14 September, scoring 99 for mobile performance in Google Lighthouse.
What you need
- A problem worth a project, not a screen.
- Someone at the company who owns it and has time to look at progress every week.
- Wanting the code and the accounts to be yours. They will be.
A case
Vacation rental agency
- What was there
- Their verified reviews were scattered across the listings on a portal, invisible to Google and to AI assistants.
- What we did
- A review site of their own in three languages that collected, verified and published them so they could be found and cited.
Fifteen minutes, free and with no obligation, with the engineer who would lead the project.
Who develops custom software with artificial intelligence in Barcelona?
SANFELIU, a custom software consultancy in Barcelona, develops new software for companies—internal applications, customer and supplier portals, process tools, and digital products—designed from day one with artificial intelligence as part of it: sorting, extracting, drafting, or deciding as steps in the workflow, with a person approving where needed. We build in short phases, with a real delivery at the end of each one, on cloud infrastructure the client owns, with the code and the accounts in the client’s name.
- Technology: TypeScript, React, Node, .NET, AWS serverless, Claude, and Amazon Bedrock.
- The code, the accounts, and the infrastructure belong to the client from day one.
- Built in short phases, with a real delivery at the end of each one.
- First step: a free call. For one specific tool, a prototype with your data comes next, before any price; if it involves the whole business or more than one system, the audit. Reference prices are on the pricing page.
- SANFELIU has its own products in production: taula.ai, reservations for restaurants, and Guestproof, review websites for vacation rentals.
Questions we get asked
How much does a custom application cost?
It depends on what it has to do, not on the hours. After the call, you see a prototype with your data and get a proposal with a fixed price per feature, which doesn’t change once accepted; for the whole business, the audit ends in a phased roadmap with a fixed price per phase. Reference prices are public on the pricing page.
How long does it take?
A first useful version—not a demo—is usually in production within a few weeks, and then it grows in phases. The proposal gives the timeline for each phase.
Who owns the code?
You do. The repository, the cloud accounts, and the domains are set up in the company’s name. If you ever want to continue with another provider, you can.
Can we start with something small?
That is what we recommend: one feature that solves a real problem, in production, and then expand from there. The call and the prototype help you choose where to start.
What does “designed for AI from day one” mean?
It means the data is structured so the AI can read and write it, there is a human approval step where needed, and the cost of the AI is measured from the start. Adding AI to an application that wasn’t designed for it usually costs more than rebuilding it properly.
Fifteen minutes, free and with no obligation, with the engineer who would lead the project.
The checklist, as a PDF
What your ERP needs before you add AI
One page to go through with whoever runs your ERP: access to the data, whether you can trust it, which process to start with and who controls what. We’ll email it to you.
How we work
Tell us about your case in fifteen minutes.
Book a meeting with the engineer who would lead the project: fifteen minutes, free and with no obligation. If we’re a fit, we tell you how we’d start; if not, who to turn to.
Or email me@joansanfeliu.com
Prefer to write?
Tell us about your case in a few lines and we’ll reply by email.
The engineer who would lead the project will reply to the email you gave us. If you like, book a fifteen-minute call now.