How I can help
I work on a project basis with founders and companies who need one person to own the technical side from start to finish.
Product: SaaS and apps, from zero to production
Architecture, development, subscriptions, deployment and operations with Laravel and Livewire. iOS and Android apps with Flutter, or with Capacitor if you already have the web app, as I did with Xpenses, released on the App Store and Google Play. The same process I follow for my own products, so I know what happens after launch. If your product is already live, I take care of it; if it has stalled or nobody wants to touch the code, I review it, tell you what can be saved and get it working again.
AI, agents and MCP: from zero to production
I work as a forward deployed engineer: I embed with your team and your business, find where AI actually saves work, and take it from prototype to fully in production. Agents that do real tasks, MCP servers that connect your systems (ERP, CRM, payments, databases) to Claude or OpenAI, natural-language search, and evals to prove it works. With permissions, logging and cost limits from day one. Xpenses and Statsdot ship their own MCP servers and Jobcedar uses Claude for search.
Payments, chargebacks and integrations
One-off charges, subscriptions, multiple gateways and reconciliation. I've been integrating Stripe, Paddle, Checkout.com, mobile carriers and app stores since 2001. I handle chargebacks: fraud prevention, fighting disputes with evidence, and keeping your dispute ratio out of the Visa and Mastercard monitoring programs. And I connect your store to ERPs, PIMs, logistics providers and in-store POS, including Spryker and AS400, with queues, retries and monitoring so an outside outage doesn't stop your sales.
Servers, DevOps and security
Linux servers, Nginx, Docker and AWS, set up and maintained by me: automated deployments, backups, monitoring and alerting. I harden servers, manage secrets and access, and review code for security, especially where payments and personal data are involved.
My own products
I design, build, bill and maintain them myself. Case studies are in Spanish.
| Product | What it does | Figure |
|---|---|---|
| FacturaYa | Invoicing for freelancers and small businesses in Spain: invoices, quotes, purchases and payments, with imports from Holded, Billin and Billage.Read the case | 3 importers |
| Jobcedar | Job search for the US and Canada. Reads listings from company career pages, normalizes them and sends alerts. Natural-language search runs on Claude.Read the case | 180,000 listings |
| Statsdot | Cookieless web analytics hosted in the EU, for several sites at once. It has an MCP server so AI assistants can query the stats, and it measures this site.Read the case | Script < 2 KB |
| Arcades.world | A US marketplace for used arcade machines, with technical filters, messaging and offers.Read the case | 68 categories |
| Xpenses | Personal budgeting for web, iOS and Android. Forecasts how much you'll have left at the end of the month, with an MCP server so AI assistants can use it.Read the case | 3 platforms |
Projects built for clients
Products I've built for other companies. Case studies are in Spanish.
| Product | What it does | Figure |
|---|---|---|
| Properties Record | US property reports: deeds, ownership and liens on the property. | US |
| Properties Record UK | Orders for Land Registry title registers, title plans and conveyancing packs, paid through Stripe and tracked order by order. | UK |
| Get My Visa Now | Travel visa applications: travelers pick passport and destination, fill in their details, pay, and get the document by email.Read the case | Online payments |
| Car-Lookup | US vehicle history reports by VIN or plate: accidents, titles, recalls and residual value.Read the case | US |
| Voice2Texts | AI transcription for audio and video, exported as text or subtitles.Read the case | 90+ languages |
| PennyGlow | Compares personal loans, debt consolidation and home equity offers in the US without affecting credit scores.Read the case | US |
Experience
I started in 1999 building websites and running Linux servers. Since then, most of what I've built has to do with money coming in: carrier billing, card gateways, subscriptions and now e-commerce for a retail chain in Germany.
Alongside that I run agenciaweb.net, where I build client projects and where my SaaS products live.
I work mostly with PHP, Laravel, Livewire, Symfony and Spryker. Also JavaScript, TypeScript, React, Next.js, Vue, Go, Python and Flutter, on MySQL, PostgreSQL, MongoDB, Redis and Solr, deployed on AWS, Docker and Nginx. For AI: Claude, OpenAI, Replicate and MCP.
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2024–now
Segmüller, lead developer and team lead
E-commerce and retail, Germany- Spryker integrations with AS400, PIM and shipping carriers.
- Payment platform for the web shop and 8 physical stores: 25% more stable transactions.
- Team of 13 developers.
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2010–2024
Digital Virgo, backend and integrations
Telecom and gaming- Global billing platform in 40 countries, up to 1,000 payment requests per second.
- Carrier billing with Netflix and Google Play for Yoigo.
- Integrations with Movistar, Swisscom, TIM, Claro, Vivo and other carriers.
- Card gateways: Stripe, Checkout.com and Paycomet.
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2001–2010
Genexies Mobile, full-stack
Music and media- Music streaming and download platform with carrier billing.
- Full-text search with Solr and Lucene over large catalogs.
- High-traffic websites for Prisacom and Etisalat.
How I work
Four things I don't compromise on, whatever the project.
Why before how
Before writing code I want to understand the business problem we're solving. The solution often turns out smaller than it first looked.
Architecture you can maintain
Simple solutions, clear boundaries between the parts of the system, and the important decisions written down. Whoever comes next has to be able to follow it.
Plan for what breaks
First I make the normal case work. Then I check what happens when an external service goes down, odd data arrives or traffic triples. With payments involved, this isn't optional.
I stay after launch
I maintain what I build. My products are still running because I look after them, and I apply the same standard to my clients' work.