Senior .NET Modernization Lead
Multi-tenant SaaS platform modernization + Azure→AWS re-platform
About Clearstone Software
Clearstone Software, LLC is a Texas-based technology company building two specialized platforms for the medical aesthetics industry:
Our Practice Management Platform — a mature, multi-tenant .NET SaaS for medical spas and clinics covering appointments, patient records (PHI), treatment planning, membership management, payments, and clinic operations. Currently running on .NET Framework 4.5-4.6 with a database-per-tenant multi-tenancy model, field-level PHI encryption, and HIPAA-aligned data-handling practices. Currently in final development for internal launch into our founder's own aesthetic clinics, followed by a coordinated stack modernization (to .NET 8/9 and ASP.NET Core) and infrastructure re-platform (Azure to AWS) ahead of commercial rollout to external med spa customers.
Our Practitioner Education Platform — a Laravel 10 + Filament 3 training and credentialing system for aesthetic practitioners, covering onboarding, skills assessment, competency monitoring, and continuing education. Built on a TALL stack (Tailwind + Alpine + Laravel + Livewire) with Vite for build tooling and AWS S3 for asset storage. Live video delivery is already integrated via Cloudflare Stream. Next phase: enterprise features, full multi-tenant SaaS launch, and AI-powered real-time practitioner feedback.
Our founder operates active medical aesthetic clinics under the Texas Lasers brand and leads a US-based aesthetic college and training institute. Every feature we ship gets tested in real clinical operations and real training environments before it reaches an external customer. We know what actually works in the aesthetic industry — not just what looks good in a demo — and that grounding shapes how we hire, how we prioritize, and how we ship.
Employment structure: All new hires begin employment via Multiplier Technologies Vietnam Company Limited (Employer of Record), with planned transition to direct employment with Clearstone Software Vietnam Co., Ltd. when we establish our Vietnamese entity in late 2026 / early 2027. This transition preserves continuity of service, social insurance, and all statutory benefits.
Work arrangement: Hybrid. You'll work 2-3 days per week from our team space in District 1 or District 3, Ho Chi Minh City, with the remaining days home-based. We value output over hours-in-chair; our office anchor days are for pair-programming, architecture discussions, and building the team.
The Role
You will lead the coordinated modernization of our mature multi-tenant SaaS platform: porting from .NET Framework 4.5-4.6 to modern .NET (.NET 8/9), migrating ASP.NET MVC 5 / Web API 2 to ASP.NET Core, refactoring EF6 code-first to EF Core, and re-platforming from Azure infrastructure to AWS — all while preserving the database-per-tenant multi-tenancy model, PHI field-level encryption, HIPAA-aligned data isolation, and business continuity for live clinical operations.
This is not a greenfield build. This is a senior technical lead role for someone who has actually done .NET Framework to .NET Core migrations at scale, has re-platformed Azure workloads to AWS, and understands what HIPAA-aligned data-handling with per-tenant isolation means at the code level. You'll manage two engineers directly (a Backend Developer and a Frontend Modernization Engineer), report to the founder, and own the sequencing and architecture of the entire modernization program.
The immediate ship comes first. The platform is approximately 90% complete for internal launch into our founder's own clinics on the current legacy stack. Your first 60-90 days finish that scope (tablet-based check-in/checkout, remaining UI cleanup, bug fixes) so we can validate the product in real clinical operations. Modernization follows — sequenced project-by-project, not big-bang, without disrupting live tenants.
Legacy → Target Stack
• Runtime: .NET Framework 4.5-4.6 - .NET 8 / 9
• Web: ASP.NET MVC 5, Web API 2 - ASP.NET Core
• Data: Entity Framework 6 - EF Core
• DI: Autofac 3 - Microsoft.Extensions.DependencyInjection
• Auth: ASP.NET Identity 2 / OWIN - ASP.NET Core Identity / OIDC
• Background jobs: Azure WebJobs - Lambda / ECS + EventBridge Scheduler
• Storage: Azure Blob Storage - Amazon S3
• Messaging: Azure Service Bus / Queues - SQS / SNS / EventBridge
• Cache/Session: Azure Redis - ElastiCache for Redis
• Database: SQL Server (Azure) - RDS for SQL Server / Aurora
• Logging/Monitoring: log4net + Application Insights - CloudWatch / OpenTelemetry / Serilog
• Hosting: Azure Cloud Service - ECS/Fargate or EKS
• Build: MSBuild / Visual Studio - dotnet CLI + CI/CD
- First 60-90 days: Take ownership of the codebase. Ship the final internal-launch scope on the legacy stack. Establish observability and deployment discipline in the existing environment.
- Migration sequencing: Design and lead the project-by-project modernization plan. Preserve DB-per-tenant model and PHI field-level encryption at every step.
- Runtime & framework porting: Lead the port from .NET Framework 4.5-4.6 to .NET 8/9. Move ASP.NET MVC 5 / Web API 2 to ASP.NET Core. Migrate EF6 code-first to EF Core with multi-context patterns and per-tenant schema management. Refactor Autofac 3 to Microsoft.Extensions.DependencyInjection. Migrate ASP.NET Identity 2 / OWIN to ASP.NET Core Identity + OIDC / OAuth 2.0.
- AWS re-platform: Design and execute the move from Azure to AWS. Replace Azure Blob with S3, Azure Service Bus / Queues with SQS/SNS/EventBridge, Azure Redis with ElastiCache, Azure WebJobs with Lambda / ECS + EventBridge Scheduler, Application Insights + log4net with CloudWatch / OpenTelemetry / Serilog. Move to ECS/Fargate or EKS on containerized .NET. Move database from Azure SQL to RDS or Aurora using AWS DMS.
- Security & key management: Own PHI field-level encryption using AWS KMS. Move secrets to AWS Secrets Manager. Establish VPC design, IAM policies, least-privilege access appropriate to HIPAA-regulated SaaS.
- CI/CD & IaC: Move builds from MSBuild / Visual Studio to dotnet CLI + automated pipelines. Establish infrastructure-as-code (Terraform or AWS CDK). Raise test coverage using xUnit / NUnit + Moq.
- Team leadership: Manage two engineers directly — sprint planning, code review, mentorship. Coordinate architecture decisions with the Laravel Lead on shared services.
- Compliance stewardship: Maintain and extend HIPAA technical safeguards through the migration. Add GDPR compliance layer for future EU rollout. Add i18n infrastructure for multi-language rollout.
- 8+ years of professional C# / .NET development
- Both modern .NET (.NET 6/7/8/9) AND legacy .NET Framework 4.x production experience
- Proven .NET Framework → .NET Core/8/9 migration experience at scale on a real production codebase
- Deep hands-on experience migrating ASP.NET MVC 5 / Web API 2 to ASP.NET Core
- Deep hands-on Entity Framework 6 → EF Core migration experience, including multi-context and code-first migration patterns
- Modern C# fluency — nullable reference types, async/await throughout, pattern matching, records, primary constructors
- Autofac → Microsoft.Extensions.DependencyInjection refactoring experience
- ASP.NET Core Identity + OIDC/OAuth 2.0 — migrated from ASP.NET Identity 2/OWIN in production
- HIPAA production implementation experience — field-level encryption, audit logging, access controls
- Multi-tenant SaaS architecture experience — ideally DB-per-tenant, with tenant resolution middleware, per-tenant schema management, rolling schema changes
- Hands-on AWS production experience: ECS/Fargate or EKS, RDS, VPC, IAM, Secrets Manager, KMS, S3, SQS/SNS/EventBridge, ElastiCache, CloudWatch
- Strong SQL Server production experience, including performance tuning and rolling schema changes
- Prior team lead experience — managed 2-4 engineers
- Excellent English communication, verbal and written
Nice to Have
- Prior experience with a full Azure-to-AWS re-platforming — the perfect-fit signal
- AWS DMS experience for SQL Server migrations
- Docker/Kubernetes for containerized .NET
- Infrastructure-as-code experience (Terraform preferred, AWS CDK/CloudFormation acceptable)
- SonarQube or similar static analysis tooling
- Serilog + OpenTelemetry observability stack
- Prior work on healthcare, wellness, med spa, or medical practice management software
- SOC 2 audit preparation experience
- GDPR compliance implementation experience
- Front-end modernization experience (jQuery/Bootstrap → React)
- Salary: USD 4,000-5,600/month gross, paid monthly via Multiplier Technologies Vietnam (Employer of Record)
- 13th-month bonus (1 month of salary, customary in Vietnam, paid every December)
- Annual salary review with merit-based increases
- Full Vietnamese statutory benefits administered via EOR: social insurance, health insurance, unemployment insurance, occupational accident and disease insurance
- 12+ days annual paid leave per Vietnamese Labor Code, plus all Vietnamese public holidays, plus sick and personal leave per Vietnamese Labor Code
- Company-owned computer for your work
- Access to our team space at Dreamplex, District 1 or District 3, Ho Chi Minh City
- Company-provided VPN, MDM, security stack, and productivity software licenses
- Direct mentorship from the US-based founder
- Direct employment transition to Clearstone Software Vietnam Co., Ltd. planned for late 2026 / early 2027, with continuity of service preserved
Working Arrangement
- Hybrid: 2-3 days per week at our HCMC team space (District 1 or 3), remainder home-based
- Core overlap hours: 9:00 AM - 1:00 PM ICT for standup and synchronous work
- Output-based culture — we value what you ship, not hours-in-chair
- Initial 60-day probation via EOR, then indefinite-term contract
Application Process
- Your CV (PDF)
- Link to your GitHub profile or technical portfolio
- Short cover note (3 paragraphs max): why you're interested, a specific .NET Framework → .NET Core migration you've led (sequencing, what nearly derailed it, what you'd do differently), and your point of view on preserving multi-tenant isolation and PHI encryption through a coordinated migration
- Earliest start date and current salary expectation in USD/month
Process timeline: ~4 weeks from application to offer given the specialist nature of the role.
