I buildsoftwareplatforms
Founder. Developer. Architect.
Founder @ VetPMS | Freelance Fullstack .NET Developer
Reynethan Leon
Fullstack .NET Developer
Netherlands-based. Off-screen you’ll find me on a snowboard, on two wheels, or reading psychology. On-screen, probably refactoring something right now.
Not just frontend or API. I handle architecture, backend, portals, mobile apps, integrations, and deployment. The full picture.
In the last three years, I’ve built production systems with teams as small as two. These run daily at well-known companies. Highlights: a fintech platform processing live transactions for major retailers; an HR system that replaced a stack of SaaS tools; a multi-tenant portal that cut onboarding from weeks to minutes.
Right now, I’m building VetPMS: AI-native practice management for veterinary clinics. Real-time speech-to-form, streaming transcription, and a modular platform designed to cut clinic admin in half.
3+
Years in production
4
Platforms shipped
3
Industries
Available 20 hours per week. Remote-first. On-site when it matters.
Projects
What I’ve built
All-in-One HR Platform
Developer, full stack
Replaced a landscape of SaaS tools with one integrated staffing platform.
The company runs its entire operation on this platform.
Pay-on-Demand Platform
Co-developer, full stack
Employees access earned salary anytime. Full technical ecosystem built with one other developer.
Live, used by major retailers nationwide. Apps in both stores.
VetPMS
Founder / CTO
AI-native practice management for veterinary clinics. The vet speaks, the record writes itself.
60+ vet professionals giving feedback. First pilot clinic lined up.
Multi-Tenant Client Portal
Architect and lead developer
Standardized portal serving multiple clients from one codebase. Automated onboarding with DNS, SSL, setup wizard.
New clients onboard in minutes, not weeks. Now the production system.
Stack
Built across layers.
I move between backend systems, product UI, data, identity, jobs, and AI features. The point is not a favorite framework. The point is shipping the right thing.
Bias
Backend-first. Comfortable in the messy middle between product, platform, and delivery.
Drag or scroll →
.NET
ASP.NET Core APIs, portals, and long-lived product systems.
C#
Business logic, services, domain-heavy work, and the hard parts.
Blazor
Full-stack .NET UI when the stack is the right fit end to end.
EF Core
Query shaping, migrations, and sane data access.
Azure DevOps
Pipelines, release discipline, and work tracking.
SQL Server
Enterprise estates, integrations, and real production constraints.
PostgreSQL
Relational foundations, migrations, reporting.
Firebase
Events, notifications, and mobile-adjacent flows.
React
Product UI that still respects speed and structure.
Next.js
Fast landing surfaces and app shells.
TypeScript
Confident iteration on the client side.
Tailwind CSS
Fast visual iteration without CSS sprawl.
Duende IdentityServer
Identity and access control when auth is part of the product.
Hangfire
Background jobs, scheduled work, and operational follow-through.
xUnit
Tests for the parts that should not fail quietly.
AssemblyAI
Speech pipelines and AI-native product features.
Git
Version control, branching strategies, and collaboration.
ASP.NET Core
Web APIs, middleware pipelines, and production hosting.
OAuth 2.0
Authorization flows, token management, and secure access.
.NET MAUI
Cross-platform mobile and desktop apps from one codebase.
Serilog
Structured logging for diagnostics and observability.
Real-time Streaming
SignalR, WebSockets, and live data pipelines.
Generative AI
LLM integration, prompt engineering, and AI-native features.
.NET
ASP.NET Core APIs, portals, and long-lived product systems.
C#
Business logic, services, domain-heavy work, and the hard parts.
Blazor
Full-stack .NET UI when the stack is the right fit end to end.
EF Core
Query shaping, migrations, and sane data access.
Azure DevOps
Pipelines, release discipline, and work tracking.
SQL Server
Enterprise estates, integrations, and real production constraints.
PostgreSQL
Relational foundations, migrations, reporting.
Firebase
Events, notifications, and mobile-adjacent flows.
React
Product UI that still respects speed and structure.
Next.js
Fast landing surfaces and app shells.
TypeScript
Confident iteration on the client side.
Tailwind CSS
Fast visual iteration without CSS sprawl.
Duende IdentityServer
Identity and access control when auth is part of the product.
Hangfire
Background jobs, scheduled work, and operational follow-through.
xUnit
Tests for the parts that should not fail quietly.
AssemblyAI
Speech pipelines and AI-native product features.
Git
Version control, branching strategies, and collaboration.
ASP.NET Core
Web APIs, middleware pipelines, and production hosting.
OAuth 2.0
Authorization flows, token management, and secure access.
.NET MAUI
Cross-platform mobile and desktop apps from one codebase.
Serilog
Structured logging for diagnostics and observability.
Real-time Streaming
SignalR, WebSockets, and live data pipelines.
Generative AI
LLM integration, prompt engineering, and AI-native features.
Process
How I work
I lead with architecture and design, not code. Delivery is always iterative unless milestones make more sense for your team. Communication is flexible: async, sync, or both. You get updates how and when you want them. I scale my approach to fit, whether I’m working solo or embedded with your team. Short-term or long-term, I deliver.
References available on request.
Contact
Ready to build?
info@reynethan.com
Available for freelance projects, 20 hours per week. I prefer to deliver from architecture to deployment.
Direct line · Fast start · From €65/hr
20 hours/week · Remote-first · On-site when it matters