// custom software, built and run
I build the toolsyour business actually needs.
Custom apps, automations, dashboards, and AI features, built around how you already work and kept running for you, at a fair price. The kind of software that turns slow, manual processes into a revenue machine: less busywork, fewer mistakes, more growth.
// what i can build
What I can build for you
From a single automation to a full custom application, built around your process instead of a template. The goal is always the same: software that quietly earns its keep.
Custom applications
Tailored applications that fit how your team actually works. I automate the manual steps, remove the workarounds, and replace the tools you've outgrown.
Workflow automation
I take the repetitive jobs eating your team's week (exports, copy-pasting between systems, manual reports) and automate them end to end, so they run on their own and stay correct.
AI features
I add AI to the tools you already use, so your team can ask in plain language and get answers, drafts, or recommendations in seconds instead of digging for hours.
Dashboards & reporting
Live dashboards built around your KPIs, plus reports that generate and send themselves, so the numbers are ready before anyone asks.
Data pipelines & warehousing
I connect your scattered tools into one reliable flow and a warehouse everyone can trust, so the numbers are always fresh and consistent. No more manual exports.
Email deliverability
Whether it's transactional mail or a marketing campaign to your whole list, landing in spam costs you leads, money, and trust. I fix deliverability at scale, set up SPF, DKIM, and DMARC, watch your sender reputation, and keep it monitored so your bulk sends actually reach the inbox.
// how it works
From scattered data to confident decisions
Four steps from scattered tools to a team that acts on numbers they trust.
Connect
No more manual exports
Store
One place, always current
Transform
Clean, consistent data
Deliver
Your team acts on it immediately
// custom applications
Replace the spreadsheet your business runs on
Every team has that one critical spreadsheet: fragile, slow, and one bad edit away from breaking. I turn it into a real application your team can trust, without changing how they work.
- Your team is productive from day one, no training needed
- Live data from your existing systems, always up to date
- Built around your process, not the other way around
- Fully hosted and maintained, zero overhead for your team
// selected work
A sense of what I build
Every project is custom, but here is the kind of thing I take on.
Analytics & reporting platform
for an email-marketing network
Their account managers used to rebuild every publisher's campaign results by hand each week to plan the next. Now it all lives in one place: filterable dashboards, automated weekly PDF reports by email, and AI recommendations that come with their reasoning, saving hours a week and freeing the team for advice and client relationships.
Company-critical data platform
for a scaling B2B SaaS
An internal data platform that connects data from across the business into a single source of truth, surfaced in a custom dashboard for revenue, churn, cohort and forecasting analytics. Built in close alignment with stakeholders in every department, it is now company-wide core infrastructure, extended with an integrated AI layer and a roadmap into further internal domains.
Automated content pipelines
Turn a product or data feed into finished, on-brand output and deliver it hands-free, replacing slow manual work that used to break constantly.
Internal tools, integrations & AI features
The smaller wins that still matter: an internal tool to retire a spreadsheet finance runs by hand, a bridge between two systems that do not talk, or an AI feature added to an app you already use.
Trusted by growing teams
Building software, automations, and data tools for teams in e-commerce, travel, media, and SaaS.
// about castara
Work smart. Be kind.
Castara is named after one of the most beautiful places in the Caribbean, a village where life moves a little slower and people live off the day's catch. I try to bring that same mindset to the work: work smart, be kind, and don't worry too much about tomorrow, because tomorrow will worry about itself.
I am Derek, a software developer based in The Hague. I build custom software (apps, automations, dashboards, AI) the way SaaS works, except built around your business instead of one-size-fits-all, then host and run it so you get a dependable tool rather than a codebase to maintain. You work directly with the person who builds it, which keeps things fair and free of agency overhead.
Alongside client work I am a partner at Risk Companion, a cloud risk-management platform, where I help shape its product, strategy, and commercial growth.
With experience across e-commerce, travel, media, and SaaS, I work remotely with clients across the Netherlands and Europe.
// contact
Have something you want built or fixed?
Tell me what is slowing you down. I'll give you an honest take on what is actually worth building, how long it would take, and what it would save you.