Portrait of Randolf Segubre

Senior Full-Stack .NET Developer

Randolf Segubre


I have spent more than nine years building and maintaining web platforms in C# and .NET across travel, healthcare and construction. I work on the backend, the Umbraco content management system, and the front end that sits on top of them, and I like the parts that usually go wrong in production: security headers, legacy upgrades, and data that has to be right.

Metro Manila, Philippines Open to senior full-stack .NET roles. Remote preferred.

  • 9+ years of professional C# and .NET
  • 3 industries: travel, healthcare and construction
  • 5 employers since 2017
  • 660+ commits across eight repositories on one client platform

Live sites I contributed to

Public websites I worked on as a developer at Hotelplan UK, client work through Cloud Employee. Anyone can open them. I describe only what a visitor can see, never code or internal detail.

Selected projects

Public work I can show. Each card says what it is, what my part was, and what is not finished.

More projects

AI Tutor

Working reference

A local, offline study app for senior .NET assessment preparation

Chat with a local language model, work through curated study topics, take mock exams and revisit past sessions, all running on the owner's own machine with no cloud model costs.

My role: Solo personal project.

  • Blazor WebAssembly front end on an ASP.NET Core 10 Application Programming Interface in Clean Architecture layers, with Semantic Kernel talking to a local Ollama model.
  • Built from scratch: sign-in with access and refresh tokens, and an encrypted vault for premium provider keys.
  • Blazor WebAssembly
  • ASP.NET Core 10
  • EF Core
  • SQLite
  • Semantic Kernel
  • Ollama

DevHub

Working reference

A local-network dashboard for my development drive

Scans the drive, sorts what it finds into projects, Windows apps and mobile apps, and lets me browse files, grab an installer, or install an Android app from a browser on the local network.

My role: Solo personal project.

  • A from-scratch Android package metadata parser and a path-traversal guard on all file access.
  • No third-party NuGet packages, and a documented session history including two real bugs caught by testing.
  • C#
  • .NET 10
  • Blazor
  • Minimal API

Galaxy Survivor

In development

A one-thumb endless roguelite space shooter for phones

A mobile game project in Unity, specified documentation-first: design, architecture, security and monetisation ethics were written down before gameplay code, then built and checked on a real device.

My role: Solo personal project, design and build.

  • Shows range beyond web work: game loops, device builds and a store-review-aware plan.

Known gap: The repository is private, so there is no source link.

  • Unity
  • C#

.NET assessment reviewer

Working reference

A senior .NET and full-stack reference with mock exams

A self-contained study reference I wrote and maintain, with topic deep dives and mock exams whose examples point at real code in BudgetPH.

My role: Author and maintainer.

  • Written as teaching material, so each topic explains the why and not only the syntax.
  • Markdown
  • C#
  • .NET

Experience

Nine-plus years of professional C# and .NET, newest first.

  1. Senior Full-Stack .NET Developer

    Cloud Employee , client Hotelplan UK

    June 2024 to August 2026 · Remote

    • Contributed full-stack development to a live, high-traffic Umbraco booking platform and its sister sites, with more than 660 commits across eight actively worked repositories.
    • Took the initiative on a Content Security Policy hardening effort across two customer-facing production sites: removed unsafe-inline and unsafe-eval, added per-request nonces, and adopted Trusted Types.
    • Diagnosed a layered Azure hosting stack (gateway with its web application firewall, content delivery rules, blob storage and app service configuration) to find which layer produced a given response header.
    • Built custom Umbraco backoffice property editors in AngularJS for editors across two content platforms.
    • Set up Model Context Protocol server integrations and shared instruction files for my own workflow, so GitHub Copilot and Claude Code follow one set of conventions.
    • C#
    • ASP.NET Core
    • Umbraco
    • Vue.js
    • AngularJS
    • SCSS
    • Azure
    • Docker
    • Jenkins
  2. Package App Senior Analyst

    Accenture , client Centene, then UnitedHealth Group

    January 2022 to June 2024

    • Remediated GitHub code-scanning findings and reviewed colleagues' code for the whole tenure, flagging redundant logic and proposing shared helpers instead of duplicated code.
    • On the UnitedHealth Group claims system: improved query-based pagination performance and fixed data-consistency and duplicate-record problems across two core applications.
    • Took part in upgrading legacy ASP.NET Core 2.x systems to ASP.NET Core 6, one closely monitored dependency step at a time.
    • Used GitHub Copilot from 2022, when the firm began encouraging its adoption to evaluate reliability and speed gains during its generative artificial intelligence rollout.
    • C#
    • ASP.NET Core
    • Razor Pages
    • SQL Server
    • GitHub
  3. ASP.NET Developer

    Collabera , client Centene (through Accenture)

    May 2020 to January 2022

    • Led the supplemental-file processing for the 834 healthcare enrolment standard (add, change, term, void, reinstatement) with minimal guidance and close quality assurance coordination, on a case-management platform spanning 19 health plans.
    • Migrated more than 500,000 member records into a repository of over one million records, and built the legacy project framework from scratch for a newly acquired state health plan.
    • Took part in upgrading the platform from .NET Framework 4.6 to 4.8, and maintained its legacy Windows Presentation Foundation desktop companion app.
    • Diagnosed ServiceNow-escalated production issues for inbound 834 processing as data or code root cause, resolving them with peer-reviewed data-correction scripts or direct code fixes.
    • C#
    • .NET Framework
    • React
    • Redux
    • MongoDB
    • WPF
  4. .NET Developer

    BCS Technology International , client Scoot Airlines

    September 2018 to March 2020

    • Built backend services for customer-facing airline booking tools, deployed on Amazon Web Services.
    • Integrated the Navitaire Dot-Rez reservation system over its Simple Object Access Protocol interface for flight-transfer management.
    • Designed the schema and Entity Framework Core Code First models against MySQL, with 90 percent backend test coverage in xUnit.
    • C#
    • ASP.NET
    • Vue.js
    • EF Core
    • MySQL
    • xUnit
    • AWS
  5. Computer Programmer

    F. Gurrea Construction, Inc.

    June 2017 to July 2018

    • First professional role: an in-house Windows desktop application that generates employment and attendance certificates, with Dapper data access against SQL Server and an editable print preview.
    • C#
    • WinForms
    • Dapper
    • SQL Server

Skills

Backend

  • C#
  • ASP.NET Core
  • ASP.NET MVC
  • .NET Framework
  • EF Core
  • MediatR
  • Clean Architecture
  • SOAP and REST integration
  • xUnit

Front end

  • React
  • Vue.js
  • Blazor
  • JavaScript
  • TypeScript
  • HTML and CSS
  • SCSS
  • Figma handoff

Content management

  • Umbraco
  • Content-type modelling
  • Models Builder
  • Custom backoffice property editors

Data

  • SQL Server
  • T-SQL
  • MySQL
  • MongoDB
  • SQLite
  • Search engine query debugging

Security

  • Content Security Policy
  • Trusted Types
  • Security headers
  • OWASP ZAP
  • JWT authentication
  • Code scanning remediation

Cloud and delivery

  • Azure diagnostics
  • AWS
  • Docker
  • Jenkins
  • Git and GitHub

AI-assisted engineering

  • GitHub Copilot
  • Claude Code
  • Model Context Protocol configuration
  • Shared instruction files

Practice

  • Code review
  • Legacy upgrades
  • Production support triage
  • Documentation-first delivery

Let's talk

Open to senior full-stack .NET roles. Remote preferred.