.NET Development for Enterprise Applications and APIs

We build ASP.NET Core applications, .NET Web APIs, and Azure-integrated back-end systems for enterprises that rely on the Microsoft ecosystem and value C# type safety, long-term support, and delivery speed.

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Enterprise .NET Development Built for the Microsoft Ecosystem

We build ASP.NET Core web applications, .NET Web APIs, and Azure-integrated back-end systems for enterprise teams where C# is established, Microsoft platform support is a requirement, and architectural quality is evaluated by the engineering team before development begins.

Our .NET practice covers Clean Architecture, Entity Framework Core optimisation, Azure AD and Key Vault integration, SignalR real-time features, .NET microservices with Polly resilience, and AI integration through ML.NET and Azure OpenAI.

We work with C# development teams building enterprise web applications, .NET APIs consumed by Angular SPAs and mobile clients, and organizations running Azure as the core infrastructure their operations depend on.

Every engagement begins with architecture documentation before a single line of application code is written: service layer design, Entity Framework schema, API contract, Azure deployment plan, AI service integration, and testing strategy are all agreed before development starts.

From Clean Architecture ASP.NET Core applications to AI-augmented back-end services integrating Azure OpenAI and Semantic Kernel, we build at the technical depth the .NET enterprise ecosystem demands from its development partners.

Since 2007, Keyideas has delivered .NET applications for financial services, healthcare, industrial operations, and enterprise SaaS businesses across the United States, United Kingdom, and Australia.

Services That Align With .NET

  • .NET development integrates seamlessly with our web design and development practice, with the same team handling the front end and ASP.NET Core APIs for better alignment.
  • .NET MAUI extends the shared C# codebase across mobile and web, keeping development aligned with the Microsoft ecosystem.
  • Our offshore software development services provide long-term .NET engineering support beyond project-based engagements.

Cities Where We Deliver .NET Development

  • In New York, Boston, and Seattle, we support finance, healthcare, and enterprise clients with Microsoft-focused .NET expertise.
  • In London and Dublin, we support financial institutions using US-based .NET stacks, combining technical expertise with EU compliance awareness.
  • In Singapore, Sydney, and Bengaluru, we deliver Azure expertise with local data residency, engineering depth, and cost efficiency.

Benchmarked Against Leading Enterprise Technology

We benchmark every .NET engagement against the architecture quality, test coverage, AI integration patterns, and Azure deployment standards set by the best .NET engineering teams in the enterprise software market.

.NET Solutions We’ve Engineered

Keyideas has built enterprise-grade .NET applications for clients in industrial operations, global energy, and B2B commerce across the US, UK, and Australia.

Industries We Know From the Inside

Keyideas has built websites, platforms, and software products across more than 20 industry verticals over 18 years. We bring direct project experience to each industry we serve, not a generalist template applied to every client brief. Select an industry below to see what we have built in your market.

.NET Technologies We Work With

We select and combine .NET, Azure, databases, APIs, testing frameworks, and supporting technologies based on application complexity, integration requirements, scalability, security, and long-term maintenance.

We Build On

We Migrate From

.NET Development Capabilities

From ASP.NET Core applications and Web APIs to Entity Framework, Azure, testing, SignalR, and microservices, we build .NET solutions around the technical and business requirements of each product.

ASP.NET Core Web Application Development

Clean Architecture Implementation for Enterprise Applications

Minimal APIs and Controller-Based API Selection

Middleware Pipeline Design and Cross-Cutting Concerns

We implement Clean Architecture separating domain, application, persistence, and API layers with defined dependency rules that keep business logic independent of the delivery mechanism. Minimal APIs suit microservices and low-ceremony endpoints; controller-based APIs suit larger systems where action filter pipelines enforce consistency across hundreds of endpoints. Middleware pipeline ordering is treated as architecture rather than configuration, because incorrect sequencing of authentication, authorization, and exception handling produces security vulnerabilities that only manifest under specific request patterns in production.

.NET Web API Design and Contract Management

RESTful API Design With Problem Detail Error Responses

API Versioning Strategy and Breaking Change Management

OpenAPI Contract-First Development With Swashbuckle

We design .NET Web APIs with resource-oriented URL structures, correct HTTP semantics, standard status codes, and RFC 7807 problem detail error responses that consuming teams handle consistently. API versioning using URL segment or header strategies with a defined deprecation timeline is implemented before the first external consumer connects. The OpenAPI specification produced by Swashbuckle is reviewed before implementation begins, so consuming teams identify interface design problems at the contract stage rather than discovering them during integration testing.

Entity Framework Core and Data Access Optimization

DbContext Configuration With Fluent API Entity Design

AsNoTracking and Explicit Include for Query Performance

EF Core Migrations for Reliable Schema Management

We configure Entity Framework DbContext with Fluent API configurations in dedicated classes, separating schema definition from the domain model so both can evolve independently. AsNoTracking on read-only queries eliminates change tracking overhead; explicit Include statements replace lazy loading so every query’s SQL is predictable and reviewable before reaching production, preventing the N+1 patterns that lazy loading produces invisibly. All schema changes go through EF Core migrations applied via CI/CD pipeline and code-reviewed like application code, never applied manually between environments.

Azure Integration for Enterprise .NET Applications

Azure Active Directory for Enterprise Authentication

Azure Key Vault for Configuration Management

Azure Service Bus and Azure Functions for Event-Driven Architecture

We integrate Azure Active Directory for enterprise single sign-on, multi-tenant authentication, and managed identity service-to-service authentication that eliminates credential rotation. Azure Key Vault replaces connection strings, API keys, and AI service credentials in application configuration from the first deployment. Azure Service Bus handles asynchronous messaging between .NET services, and Azure Functions provide serverless event-driven processing that extends .NET applications without adding to the web API surface that consumes dedicated compute resources.

Authentication and Authorization in .NET Applications

ASP.NET Core Identity for User Account Management

Policy-Based Authorization for Business Rule Enforcement

JWT Bearer Authentication for Stateless API Consumers

We implement ASP.NET Core Identity for registration, email confirmation, two-factor authentication, and OAuth integration with an extensible custom user store. Policy-based authorization keeps authorization rules in testable requirement and handler classes rather than ad hoc role checks scattered across controllers that grow inconsistent as the application evolves. JWT bearer authentication for SPA and mobile API consumers covers Key Vault signing key management, validation parameters, and the access and refresh token lifecycle suited to each consumer type’s session behavior and security requirements.

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SignalR for Real-Time .NET Application Features

SignalR Hub Design and Bidirectional Communication

Azure SignalR Service for Multi-Instance Deployments

Hub Authentication With ASP.NET Core Middleware

We implement ASP.NET Core SignalR for live notifications, collaborative editing features, and real-time dashboard updates, with transport negotiation between WebSockets, Server-Sent Events, and long polling handled automatically. The Azure SignalR Service backplane routes messages between clients connected to different server instances without sticky sessions on the load balancer. Hub authentication integrates with ASP.NET Core middleware, passing the JWT through the WebSocket query string because WebSocket connections cannot carry Authorization headers during the upgrade handshake.

.NET Microservices and Cloud-Native Architecture

Bounded Context Decomposition and Service Boundary Design

.NET Aspire for Cloud-Native Application Orchestration

Polly Resilience Policies and Health Check Endpoints

We design .NET microservice boundaries around bounded contexts with each service owning its data store and exposing data only through a defined API. .NET Aspire provides cloud-native orchestration for distributed .NET applications, simplifying the service discovery, configuration, and observability setup that microservice deployment on Azure requires. Polly resilience policies implement retry with exponential backoff for transient failures and circuit breakers for consistently failing downstream services; ASP.NET Core health check endpoints serve Kubernetes readiness probes, Azure App Service health integration, and load balancer configuration.

.NET Testing With xUnit and WebApplicationFactory

xUnit Unit Tests for Service Layer Business Logic

WebApplicationFactory Integration Tests for Full Pipeline Coverage

FluentAssertions for Readable CI Failure Messages

We write xUnit unit tests for .NET service layer logic with Moq mocks for repository and external adapter dependencies, verifying business rules independently of infrastructure. WebApplicationFactory integration tests create a test server running the full application pipeline, making real HTTP requests that verify middleware, authentication, and Entity Framework against a test database, catching integration failures that unit tests with mocked dependencies cannot surface. FluentAssertions produce failure messages that communicate what was expected and what was received, reducing investigation time for failing CI builds significantly.

AI Integration With ML.NET and Azure OpenAI

ML.NET for On-Premises Machine Learning Model Inference

Azure OpenAI and Semantic Kernel for LLM-Powered Features

.NET Aspire and Microsoft.Extensions.AI for AI Service Orchestration

We integrate AI and machine learning capabilities into .NET applications using ML.NET for on-premises model inference within C# code without a Python service layer, Azure OpenAI Service through the Azure.AI.OpenAI SDK for generative AI features including chat completion, embedding generation, and function calling, and Semantic Kernel for orchestrating LLM-powered workflows within ASP.NET Core applications. Microsoft.Extensions.AI provides the abstraction layer that allows switching between AI providers without rewriting application code. AI service calls are wrapped in Polly resilience policies covering retry, circuit breakers, and timeouts appropriate to LLM endpoint latency characteristics.

.NET for Financial Services and FinTech

Trading Platform and Investment Management Back-End

Payment Processing and Open Banking API Development

Regulatory Compliance and Audit Trail Architecture

Financial services and FinTech businesses choose .NET for C# type safety, Azure Active Directory enterprise authentication, and the audit trail architecture that regulatory compliance requires. We build trading platform back ends, investment management APIs, payment processing services integrating with open banking providers, and the regulatory reporting systems that financial institutions need from a technology stack with Microsoft’s enterprise support commitment behind it. EF Core migrations provide the schema change audit trail that financial services change management requires, and Azure Key Vault stores the cryptographic material that payment processing security demands.

.NET for Healthcare and Enterprise Compliance

HIPAA-Aware Healthcare Platform and Clinical API Development

EHR and Clinical Workflow Integration With .NET

Enterprise Intranet and Operations Platform Development

Healthcare organizations and enterprise businesses choose .NET for compliance-aware architecture, Azure AD integration with existing Microsoft 365 infrastructure, and HIPAA-aware deployment options that Azure’s regulated workloads capability provides. We build clinical workflow APIs, EHR integration back ends, patient portal applications, and the enterprise operations platforms that large organizations need when the Microsoft ecosystem is already the established standard. .NET’s long-term LTS support commitments align with the enterprise IT lifecycle planning that healthcare procurement, government IT governance, and regulated industry change management processes require.

How We Collaborate With Our Clients

We use industry-leading tools to ensure smooth communication, efficient development and transparent project management

Project
Management

Plan tasks, timelines, and project resources efficiently.

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Development

Build scalable solutions with clean and secure code.

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Maintenance

Monitor performance, fix issues, and manage updates.

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Design

Create wireframes, UI designs, and interactive prototypes.

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Communication

Conduct meetings and discussions to stay aligned.

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Frequently Asked Questions on .NET Development

Questions from engineering teams and technical decision-makers about .NET development with Keyideas.

Choose .NET when the organization is in the Microsoft ecosystem using Azure, Active Directory, SQL Server, or Office 365, when C# strong typing is a requirement, or when the team needs native AI integration through ML.NET or Azure OpenAI within a C# codebase. For high-concurrency APIs with I/O-bound workloads and teams running a unified JavaScript stack, Node.js is often more practical. The decision is primarily driven by the existing team and infrastructure, not by performance benchmarks.

Yes. ML.NET provides on-premises machine learning model training and inference within C# applications without requiring a separate Python service. The Azure.AI.OpenAI SDK integrates Azure OpenAI Service for chat completion, embedding generation, and function calling directly in .NET code. Semantic Kernel orchestrates LLM-powered workflows within ASP.NET Core applications. Microsoft.Extensions.AI provides a standard abstraction layer across AI providers. .NET Aspire handles cloud-native orchestration for applications combining .NET services with AI endpoints on Azure.

Entity Framework Core for applications where a full ORM with migrations, relationships, and LINQ query support reduces data access code volume. Dapper for read-heavy endpoints where hand-written SQL produces more efficient queries for specific access patterns. Both coexist in the same application, with EF handling writes and relationship management and Dapper handling the read queries where SQL control matters most for performance at scale.

Azure Key Vault with Managed Identity authentication from the first deployment. Connection strings, API keys, and Azure OpenAI API keys never appear in appsettings.json, environment variables, or version control. Azure App Service Key Vault references allow secrets to be read at startup without any credential for Key Vault itself. This approach eliminates the most common .NET Azure security gap and applies to AI service credentials with the same discipline as database connection strings.

Yes. We start with a codebase audit covering architecture quality, Entity Framework query patterns, test coverage, .NET version currency, Azure configuration quality, AI integration patterns if applicable, and security posture. The audit produces an honest assessment and a prioritised remediation plan. We have inherited .NET codebases with business logic in controllers, lazy loading producing N+1 queries on every page load, no migrations, and no tests. Each of those problems is addressable with a defined remediation plan.

An ASP.NET Core Web API for a standard web or mobile application takes 10 to 16 weeks. A full enterprise web application with Azure integration takes 16 to 28 weeks. An application including AI integration through Azure OpenAI or ML.NET adds 2 to 6 weeks depending on the complexity of the AI features. A .NET microservices migration from a monolith takes 20 to 36 weeks. Timeline is confirmed after the technical specification is produced and the full integration scope including AI services is understood.

Projects start at $5,000 for a Strategic Foundation build covering core ASP.NET Core implementation, basic API or web application, and standard Azure deployment. A Next-Level Growth engagement at $10,000 adds Clean Architecture, Azure AD and Key Vault integration, and a full test suite with CI/CD. The Accelerated Competitive tier at $20,000 covers .NET microservices, SignalR real-time features, AI integration through ML.NET or Azure OpenAI, load testing, and a security audit. Enterprise Partnership is $3,300 per month for a dedicated developer with a single point of contact and project collaboration tools.

A senior .NET developer at a US agency bills at $150 to $250 per hour. At a UK agency, the equivalent is £100 to £180 per hour. A typical enterprise .NET project costs $50,000 to $150,000 at a US agency and £35,000 to £100,000 at a UK agency. The same project at Keyideas falls within our $10,000 to $20,000 project tiers. The cost difference reflects India office economics, not engineering quality.
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