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Websites that sell
- Premium marketing sites and portfolios, mobile-first
- Inquiry forms that capture clean, complete leads
- SEO basics, fast loading, and deployment under your own accounts
MK Castro — Web & Software Studio
The studio
A small studio with a big-platform standard. We build the software service businesses run on, from the first inquiry to the final invoice.
Who we are
Depth, not just breadth
MK Castro is a small web and software studio. We build the software service businesses actually run on: the website that wins the inquiry, the booking flow that turns it into a job, and the back office that keeps the money, stock, and paperwork straight.
We are deliberately small. You deal directly with the people writing your code, with senior engineering judgment on every project. No account managers, no hand-offs to a junior team, no mystery about who is doing the work.
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What we do
Six fronts, one standard: everything ships, everything survives.
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Booking & client flows
- Inquiry intake, quoting, and booking workflows
- Client portals with status tracking and document upload
- Payment milestones, contracts, and automated email notifications
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Back-office systems
- Bespoke replacements for paper, binders, and Excel trackers
- Accounting, inventory, supplier, and worker records
- Dashboards and reports that tell you where the business stands
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Business assistants
- Private AI assistants running on your own server
- Wired into your bookings, clients, calendar, and numbers
- Daily briefings, reminders, and drafted replies
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Support & modernization
- Fixes, updates, and hosting help for existing websites
- Legacy systems rebuilt without losing the business logic
- Ongoing partnerships that keep shipping the next improvement
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Infrastructure
- Cloud deployments on Vercel, AWS, DigitalOcean, and Linode
- CI/CD pipelines, backups, and zero-downtime releases
- Everything set up in accounts you own, with no markup on the bills
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Philosophy
We believe great software is:
Understandable before it is clever
Observable before it is optimized
Simple in the best possible way
Great software is straightforward, easy to extend, and hard to break.
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The founder
The person behind the shipping record.
Founder & Lead Engineer
Mike Castro
Mike founded MK Castro after more than ten years building production systems across fintech, enterprise SaaS, and consumer platforms, including three turns as CTO.
He has designed APIs that sustain 300+ requests per second with sub-200ms responses, run 100+ zero-downtime deployments, taken fintech platforms through PCI DSS and BSP compliance, and led engineering teams of up to 12. Every studio project gets that same standard.
- 10+ years shipping production software
- Three-time CTO
- PCI DSS + BSP compliance delivered
- MS Information Technology
The bottom line
Built to last
We do our best work where the business is messy and the stakes are real: sorting out tangled processes, replacing the spreadsheets nobody trusts, and leaving every system better than we found it. We build software that lasts.