ASP.NET Core APIs
Minimal APIs and MVC controllers, OpenAPI 3.1 with NSwag or Microsoft.OpenApi, FluentValidation, MediatR for CQRS, vertical slice architecture, output caching, rate limiting middleware.
Services
.NET Development Services for US & EU Enterprises and Regulated SaaS
Senior .NET engineering for enterprise and regulated SaaS: .NET 9 (and .NET 10 LTS from Nov 2025) with ASP.NET Core minimal APIs and MVC, EF Core 9 on SQL Server or Postgres, MassTransit on RabbitMQ or Azure Service Bus, Blazor Server and WebAssembly, MAUI for cross-platform, and clean migration off .NET Framework 4.x onto modern cross-platform .NET. We ship enterprise-grade C# without enterprise-grade bureaucracy. Dedicated teams from 12,000 EUR/month, project sprints from 25,000 EUR. Evaluating the stack first? See our .NET capabilities and when to choose it for enterprise.
9+Years in business
80+Senior engineers on staff
120+Projects delivered
71Client NPS
GDPR-aligned · ISO 27001 ready · SOC 2 Type II in progress · HIPAA-capable · CCPA-acknowledged · CET workday with 9 AM–1 PM ET overlap
.NET is the right call when your customers are enterprises with Azure or on-prem Windows commitments, when your domain has rich types and long lifetimes (insurance, banking, healthcare, logistics, manufacturing), and when you want a stack where async/await, source generators, AOT compilation and a serious JIT all come standard. We build ASP.NET Core APIs, Blazor and MAUI clients, MassTransit-based event-driven services, EF Core 9 against SQL Server and Postgres, and Azure-native workloads on App Service, Container Apps, AKS and Functions. Our .NET engineers average 10+ years in C# and have shipped systems regulated under PCI DSS, HIPAA and EU DORA. We are GDPR-aligned · ISO 27001 ready · SOC 2 Type II in progress.
What we build with .NET
Microservices + messaging
MassTransit on RabbitMQ, Azure Service Bus, or Amazon SQS. Saga orchestration, outbox pattern, exactly-once semantics, dapr for cross-language polyglot estates.
Blazor + MAUI clients
Blazor Server, Blazor WebAssembly, and Blazor United (.NET 8+) for component-driven web. MAUI for iOS, Android, Windows and macOS desktop from one C# codebase.
Auth + multi-tenancy
Microsoft Entra ID (Azure AD), Duende IdentityServer, Auth0, Okta. OIDC, SAML 2.0, OAuth 2.1, B2B and B2C tenants, SCIM provisioning, fine-grained authorisation with OpenFGA or built-in policy authorisation.
Data + EF Core 9
EF Core 9 with SQL Server, Postgres (Npgsql) or Azure SQL, Dapper for hot paths, Marten or EventStoreDB for event sourcing, ClickHouse or Synapse for analytics.
.NET Framework → .NET modernisation
Migrating .NET Framework 4.5/4.7/4.8 and WCF/WebForms onto .NET 8/9/10 cross-platform. .NET Upgrade Assistant, then manual cleanup of System.Web, AppDomain, remoting and WCF dependencies.
Stack and tooling
.NET 9
.NET 10 LTS
C# 13
ASP.NET Core
Minimal APIs
Blazor
MAUI
EF Core 9
Dapper
MediatR
MassTransit
RabbitMQ
Azure Service Bus
SignalR
SQL Server
PostgreSQL
Azure App Service
AKS
Container Apps
Azure Functions
How an engagement runs
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01
Discovery
1–2 weeks: read the .csproj / sln, identify .NET Framework versus .NET Core / 6/8/9 mix, profile EF Core or NHibernate queries, decide vertical-slice vs onion architecture, and write the ADR before any code lands.
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02
Foundation
Sprint 1–2: SDK-style projects, Central Package Management, .editorconfig + analyzers (StyleCop, Roslynator), Azure DevOps or GitHub Actions pipelines, container builds, OpenTelemetry to Application Insights / Datadog, blue/green deploys.
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03
Build
Two-week sprints, trunk-based, feature flags via Microsoft.FeatureManagement or LaunchDarkly, xUnit + FluentAssertions + Testcontainers for integration tests, NBomber for load testing, contract tests with Pact.
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04
Operate
On-call handoff (PagerDuty / Azure Monitor alerts), SLO dashboards, EF Core slow-query review monthly, Azure / AWS cost review quarterly, NuGet upgrades via Renovate or Dependabot.
Engagement models
Dedicated team
2–6 senior engineers embedded in your roadmap, daily standup in your channel, your repo, your CI, your on-call. Best for product roadmaps with a 6+ month horizon. From 12,000 EUR/month.
Project sprint
Fixed-scope, fixed-budget delivery: discovery + MVP + first production release. Best for new product lines, validated PoCs that need hardening, and stand-alone modules. From 25,000 EUR.
Staff augmentation
One or two senior engineers slotted into your existing squad, your stand-up, your process. Best for filling a known capability gap without disturbing team structure. From 7,500 EUR/month per engineer.
Three-month minimum on all tiers, month-to-month thereafter with 30 days notice. NDA, DPA, and IP assignment signed before kickoff.
What .NET Development Costs — and What Drives the Price
Most agencies keep the number for a sales call. Here are our published US & EU planning ranges so you can budget before discovery. Every engagement is scoped individually, but these three bands cover the common path from a fixed-scope build to a dedicated team that owns the codebase long-term.
Project sprint
From 25,000 EUR · fixed scope. Discovery + MVP + first production release. Best for new product lines, validated PoCs that need hardening, and stand-alone .NET modules. Board-ready delivery on a fixed budget.
Dedicated .NET team
From 12,000 EUR / month. A 2-engineer pod (senior + mid, plus fractional tech lead and DevOps); standard squads run 4–6 engineers at 28,000–42,000 EUR/month with QA, DevOps and PM. Your repo, your CI, your on-call.
Staff augmentation
From 7,500 EUR / month per engineer. One or two senior C# / .NET engineers slotted into your existing squad and process. Best for filling a known capability gap without disturbing team structure.
What moves the number: how much legacy you carry (a greenfield ASP.NET Core service sits well below an incremental .NET Framework 4.7 / WCF / WebForms migration of a 500k-LOC monolith behind a YARP side-by-side host); how many client surfaces you need (an API-only backend vs Blazor United web plus MAUI iOS/Android/desktop from one codebase); your data and messaging complexity (a single EF Core 9 database vs event-sourced services on MassTransit with saga orchestration and the outbox pattern); and domain compliance depth (PCI DSS, HIPAA BAAs, or EU DORA ICT third-party registers and resilience testing raise the bar and the evidence workload). A clean greenfield build under a standard DPA sits at the bottom of a band; a regulated migration writing to production financial or health systems sits at the top. Azure / AWS cloud fees are billed on your own accounts, so you keep the cost lever. Three-month minimum on all tiers, month-to-month thereafter with 30 days notice.
Selected related work
Manufacturing · E-commerce
REHAU
B2B e-commerce and product configurator for a global polymer manufacturer with multi-region pricing, stock and dealer workflows.
LegalTech · Mobile · CRM
Signatory Pro
Native iOS and Android e-signature clients with a Symfony + React CRM for a cross-border law firm — KYC onboarding and a defensible evidence trail for US & EU matters.
Auto · FinTech
AutoFinance
Dealer-facing web platform funneling every auto-financing enquiry into a single tracked queue with Bitrix24 CRM sync.
Industries We Build .NET Systems For
.NET earns its slot in domains with rich types, long lifetimes and a regulator in the room. We pair senior C# engineering with domain-specific conformance across US & EU markets, and share delivery with our enterprise software and cloud & DevOps teams when the system fronts legacy .NET Framework estates or Azure-native infrastructure.
FinTech & Banking
Lending, payments and dealer-finance platforms on ASP.NET Core with PCI DSS controls and EU DORA ICT third-party registers and resilience testing — the kind of tracked, CRM-synced queue behind our AutoFinance dealer build.
FinTech →HealthTech
HIPAA-capable .NET services with BAAs via Azure HIPAA-eligible services, EU-region data residency, PII encrypted with customer-held Key Vault or KMS keys, and documented data flows for the auditor your reviewer expects.
HealthTech →Logistics & Mobility
Route-planning, real-time tracking and in-app workflows over constantly changing state — the kind of EU-hosted backend behind our xRouten last-mile build for a German operator, delivered on event-driven .NET services.
Logistics →Manufacturing & Retail
B2B commerce, product configurators and ERP integration — multi-region pricing and dealer workflows as on our REHAU build, and bidirectional 1C sync for a live auto-parts catalog where prices shift hourly.
Retail →Why US & EU teams pick YuSMP for .NET development
GDPR-aligned · ISO 27001 ready · SOC 2 Type II in progress · HIPAA-capable · CCPA-acknowledged
Senior engineers, not body shop
Every engineer on your account has 8+ years of production C# / .NET experience. No bait-and-switch from the senior who sold the deal to a junior who actually ships.
CET workday + US overlap
CET-aligned squads with a guaranteed 9 AM–1 PM ET overlap for US clients — four hours of synchronous work per day, async docs for the rest. No 3 AM standups for anyone.
Compliance-fluent delivery
GDPR DPAs, SOC 2 Type I/II readiness, EU DORA for financial services, HIPAA controls for US healthtech, CCPA notices, EU AI Act for AI features. The compliance work is built into the sprint, not bolted on at audit time.
For regulated workloads we work directly with your auditor or fund's technical advisor and prepare evidence to the standard the reviewer expects — not the standard a generalist consultant assumes.
What clients say
Real-time ERP sync for an auto-parts catalog is harder than it looks — prices shift hourly and the catalog changes constantly. YuSMP built a bidirectional 1C integration that just works, with a clean storefront customers navigate without friction.
A retail chain with dozens of locations needs document workflows that non-technical staff can follow without training. YuSMP built an internal DMS with approval chains, versioning, and role-based access that our compliance officer called the cleanest system we have ever deployed.
Frequently asked questions
Why pick .NET in 2026 over Java, Node.js or Go for enterprise workloads?
.NET wins when your customers live in Azure or run on-prem Windows, when your domain is rich and benefits from C# records, pattern matching and source generators, and when you want first-class native AOT, async/await and ValueTask without the runtime tax of the JVM. Pick Java when your operations team is already on JVM observability and the talent pool locally favours it. Pick Node.js for I/O-heavy web BFFs. Pick Go for static binaries you ship to edge or CLI. We run polyglot teams and recommend .NET only when it earns the slot.
Which .NET versions do you standardise on, and when do you adopt .NET 10?
.NET 9 (STS, supported through May 2026) is current default. .NET 10 LTS lands November 2025 and becomes our new-build default by December 2025, supported through November 2028. C# 13 with collection expressions and primary constructors. We migrate STS-pinned codebases to the next LTS before STS support expires — never let an unsupported runtime sit in production. EF Core 9 default, EF Core 10 once the .NET 10 ecosystem catches up Q1 2026.
Do you handle EU data residency, GDPR, DORA and HIPAA for .NET apps?
Yes. Default deployment is Azure West Europe, North Europe, Germany West Central or France Central; AWS eu-central-1 / eu-west-1 for cross-cloud; on-prem Windows Server / RHEL where the regulator requires it. PII encrypted with Azure Key Vault or AWS KMS keys held in customer tenant. We ship GDPR Article 28 DPAs, DPIAs for high-risk, Article 30 records. For DORA (EU financial services, Jan 2025) we provide ICT third-party register documentation, incident classification, and resilience testing artefacts. HIPAA-capable for US healthtech with BAAs in place via Azure HIPAA-eligible services.
How do you migrate a .NET Framework 4.7 / WebForms / WCF monolith?
Incremental, never big-bang. Step 1: .NET Upgrade Assistant for low-risk projects (class libraries, console apps). Step 2: side-by-side host — new ASP.NET Core endpoints behind YARP reverse proxy in front of the legacy IIS app, route by URL. Step 3: replace WCF with gRPC or REST + MediatR contracts. Step 4: replace WebForms screens one bounded context at a time with Blazor or React. Typical 500k-LOC enterprise monolith takes 9 to 14 months with no customer-visible downtime and no feature freeze.
Can you build Blazor (Server / WASM / United) production apps in 2026?
Yes. Blazor United from .NET 8 (and refined in .NET 9/10) is now the default for new internal-tools and B2B SaaS UIs — one component model, render-mode chosen per route (Server, WASM, SSR, or auto). Blazor Server still wins for low-latency LAN apps with rich state. Blazor WebAssembly with AOT for offline-capable B2C. We have shipped a 240-screen Blazor United B2B SaaS with sub-100 ms TTI on cached routes and full keyboard-driven UX for power users.
What does pricing look like for a .NET dedicated team or project sprint?
Dedicated teams start at 12,000 EUR/month for a 2-engineer pod (typically 1 senior + 1 mid plus fractional tech lead and DevOps). Standard squads are 4–6 engineers at 28,000–42,000 EUR/month with QA, DevOps and PM. Fixed-scope project sprints (discovery + MVP + first production release) start at 25,000 EUR. All engagements include CET workday with 9 AM–1 PM ET overlap for US clients, NDA + DPA + IP assignment signed before kickoff, three-month minimum, then month-to-month with 30 days notice.
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