Alejandro Castro · Software Architect & Fractional CTO · Costa Rica / Remote
When off-the-shelf software won't fit,
I build what does.
Senior technical judgment and hands-on delivery in one seat. Most engagements start with a bounded architecture diagnostic — one to three weeks, fixed price, ending in a decision, not a proposal. From there: fixed-price, milestone-gated platform builds, or fractional CTO leadership where you need the seat. Private client portal: you always know where your project stands. I have owned payment systems across 100+ gateway integrations and hundreds of millions of dollars in transactions, and I still ship critical-path code.
I work with finance, payments, and operations leaders who need systems that fit how the business actually runs — and with founders who need senior technical judgment and hands-on delivery in one accountable person.
One Engagement. Three Capabilities.
Not three services packaged together. One service — building your platform — that naturally requires all three.
Strategy
What to build and why. CTO-level judgment on scope, priorities, and technology choices so you don't waste time or money building the wrong thing.
Architecture
How to build it so it scales. Real architectural decisions — auth, APIs, databases, deployments — designed with 36 years of real-world experience.
Delivery
Actually building it. Hands-on, AI-accelerated development. Clean code, deployed to production, handed over with documentation.
Start here
Bounded Architecture Diagnostic
$5,000 to $12,000 fixed, 1 to 3 weeks. A scoped review of the system you are stuck on, ending in a written build-vs-buy-vs-rent recommendation you can act on with or without me.
Fixed-Price Platform Build
$20,000 to $80,000 fixed, milestone-gated, 50% deposit. Scoped to how your business actually runs, with stop/continue gates at each milestone.
Fractional CTO — Finance, Payments & Operations Systems
$6,000 to $10,000 per month, 90-day minimum. Architecture, roadmap, build-vs-rent decisions, and critical-path code, about one day a week.
Not hourly billing. Not staff augmentation. Not 24/7 on-call, SEO, or hosting. One accountable person who decides and ships.
Fixed price, milestone-gated
You know the cost before we start, and every milestone is a stop/continue gate.
Private Client Portal Included
- ✓Live tasks, tickets, and progress tracking
- ✓No black box — you always know where things stand
- ✓No scope creep. No surprises. Just delivery.
Platforms I've Built
Each one built end-to-end: strategy to architecture to delivery.
AIDA — Enterprise Tax Compliance Platform
Costa Rican VAT (IVA) reconciliation rebuilt from scratch: 1.05M import rows, 6 generated reports, and a 4,900-line tax engine that replaced a legacy VBA macro.
Tools Project — Self-Hosted Project Management Hub
A vertically integrated project platform with 21 database tables, polymorphic activity feeds, dual-mode auth, Kanban boards, and a full CRM pipeline — no Redis, no Celery, no message queue.
Tools Dashboard — Multi-Tenant SaaS Admin Platform
A multi-tenant admin platform with Kong 3.4 gateway (WAF + 3-tier rate limits), Google OAuth + TOTP 2FA, four databases, and an OAuth app-store that logs users into other apps with one click.
Alejandro Castro — senior technical judgment and hands-on delivery.
Most software engagements separate strategy from execution. Consultants advise but don't ship. Freelancers code but don't architect. Agencies promise everything and deliver less.
I lead every engagement from strategy to launch. CTO-level judgment on what to build. Architect-level design on how to build it. Hands-on delivery to get it done. When the work calls for it, I bring in proven collaborators — but I remain your single point of contact and accountability.
Fixed price. Milestone-gated. No surprises.
“I don't just advise. I build. Your platform, shipped.”
Ready to Build Your Platform?
One 30-minute call to see if we're a fit. No pitch. No pressure. Just a conversation about what you need to build.
Most engagements start with a bounded architecture diagnostic: $5,000 to $12,000, 1 to 3 weeks. Fixed-price platform builds: $20,000 to $80,000, milestone-gated, 50% deposit. Fractional CTO: $6,000 to $10,000 per month, 90-day minimum.