zShuck × design#01
Launch
Good for
New brands and products that need to look right and get found from day one.
Includes
- Brand identity
- Website or landing page
- SEO and GEO setup
- Analytics and tracking
Totalmade to measure
Rubén Pérez · aka zShuck · Barcelona
I build AI agents and the products around them.
Software AI engineer and product engineer. I put agents into production with Claude, Gemini and OpenAI, build the product around them and grow it with funnels that convert. Design and brand included when you need the whole pack.
- AI agents in production
- Product strategy
- MVPs
- Funnels
- Conversion
- Lead generation
- Growth experiments
- Onboarding
- Brand + product + code
- SEO & GEO
- Analytics
- Automation
What I do
Four things, done properly.
- 01
AI agents in production
Agents that run real workflows in production, not demos. Wired to your tools and data, with evals, guardrails, human handoff and cost tracking. Claude, Gemini or OpenAI, whichever the job needs.
Claude · Gemini · OpenAI · MCP · Evals
- 02
Product engineering
From a rough idea to a product people use. MVPs, SaaS features and internal tools, built full stack, plus the product calls that come with shipping.
React · Next.js · Node · Ruby · Python
- 03
Growth engineering
Funnels, landing pages and onboarding that convert. Lead capture wired to your CRM, A/B tests, tracking and attribution, so every change shows up in the numbers.
Funnels · CRO · Leads · A/B tests · Analytics
- 04
Found by Google and by AI
Fast sites with clean structure and structured data, so they rank on Google and get recommended by ChatGPT, Gemini and Perplexity. Ask cecillorsan.es.
SEO · GEO · llms.txt · Core Web Vitals
AI agents in production
Agents that do the job, not the demo.
These are the agents I design, build and run in production. Each one plugs into the tools you already use and gets measured like any other part of the product.
agent.log
A simulated run. The real ones log a lot more.
A simulated run. The real ones log a lot more.
What production means
- Evals before launch and on every change
- Guardrails, permissions and PII handling
- A human in the loop where mistakes are expensive
- Tracing and monitoring for every run
- Cost and latency budgets per task
- The right model per job: Claude, Gemini or OpenAI
Built for
- SaaS
- E-commerce
- HR tech
- Fintech
- Agencies
- Professional services
- A-01Customer support agentsZendesk · Intercom · WhatsApp · RAG
- A-02Lead qualification and sales agentsHubSpot · Salesforce · Pipedrive · Enrichment
- A-03Document and back-office agentsOCR · Structured output · ERP · Review queues
- A-04In-product copilotsTool use · Streaming UI · Permissions
- A-05Content and marketing agentsMulti-agent · SEO · GEO · Human review
- A-06Internal knowledge and ops agentsMCP · Slack · Notion · Drive
Selected work
Things I've built and shipped.
Packs
Brand, product, code and growth. One team.
I work closely with product designers and brand designers, so you don't have to hire and coordinate three studios. Pick a pack or mix your own.
- zShuck × design#02
Product
Good for
Taking an idea to a product people actually use.
Includes
- Product discovery
- UX and UI design
- MVP built full stack
- AI features where they help
Totalmade to measure
- zShuck × design#03
Growth
Good for
Companies with traffic that want more leads and customers out of it.
Includes
- Funnel audit
- Landing pages and A/B tests
- Lead capture into your CRM
- Dashboards and attribution
Totalmade to measure
- zShuck × design#04
AI agent
Good for
Teams that want an agent doing real work, not another demo.
Includes
- Use case workshop
- First prototype in days
- Production agent with evals
- Monitoring and handover
Totalmade to measure
Now
What I'm up to
Updated November 2026
- Building
- AI agents in production with Claude and Gemini
- Shipping
- Product features, front to back
- Growing
- Funnels, conversion and leads for the brands I work with
- Playing
- Strategy and RPGs. One more turn, always
- Automating
- My flat, one smart plug at a time
Writing
Notes from the terminal
Articles about AI, tools and the craft of building software.
01 · AI
· 8 min read
Claude Code in 2026: the development companion you've been waiting for
How Claude Code changed the way I program in 2026, from refactoring legacy code to debugging the weird stuff, and where it still falls short.
Read article02 · Setup
· 15 min read
My essential hardware setup for programming in 2025
The laptop, peripherals, audio and small accessories I use to code from anywhere without carrying a bag full of cables.
Read article
FAQ
Quick answers
Who is zShuck?
zShuck is Rubén Pérez Herrando, a software AI engineer and product engineer based in Barcelona, Spain. zShuck is the name I've used online for years.
What do you build?
AI agents in production on Claude, Gemini and OpenAI models, full stack products with React, Next.js, Node.js, Ruby and Python, and the growth side around them: funnels, landing pages, lead capture and websites that Google and ChatGPT can find.
What kind of AI agents can you put in production?
Customer support agents, lead qualification and sales agents, document and back-office agents, copilots inside SaaS products, content and marketing agents, and internal knowledge agents connected through MCP. Always with evals, guardrails, monitoring and a human in the loop where it matters.
Do you work on growth and conversion?
Yes. I build and improve funnels, landing pages and onboarding, wire lead capture into your CRM, set up tracking and A/B tests, and use the data to decide what to ship next.
Can you take care of design and branding too?
Yes, through packs. I work closely with product designers and brand designers, so we can take a project from brand identity and UX to build, launch and growth with one team.
What is GEO?
Generative engine optimisation: making a website easy for AI assistants to read, trust and cite. I did it for the painter Cecilia Llorca (cecillorsan.es), so people can find her through ChatGPT and not only through Google.
Can I hire you?
Yes. I take on freelance projects and collaborations, remote or in Barcelona. Email ruben@zshuck.com or use the contact form.
Which languages do you work in?
Spanish, Catalan and English.
Got an idea?
Let's build something with personality.
Agents, products, funnels, a whole brand or a weird experiment. Tell me about it.