Senior .NET Developer LINQ

Senior / Principal .NET Developer – LINQ, Expression Trees & EF Core Internals

REMOTE

Role Summary

We are seeking a senior-level .NET engineer who understands how modern data-access frameworks are constructed, not just consumed. This role is focused on building the core execution and query engine of the platform.

The ideal candidate has deep, hands-on experience with System.Linq.Expressions, including manually constructing and rewriting expression trees at runtime, and a strong understanding of Entity Framework Core’s internal query translation pipeline. This is not a CRUD or surface-level application role. You will be designing infrastructure-level components that other developers build on top of.

Key Responsibilities

Expression Trees & Query Infrastructure

• Design and implement dynamic query engines using System.Linq.Expressions

• Manually construct, inspect, and transform expression trees at runtime

• Implement custom ExpressionVisitor logic to rewrite queries for optimization, compatibility, or dynamic behavior

• Treat LINQ expressions as data structures rather than syntax sugar

Entity Framework Core & SQL Translation

• Work deeply with Entity Framework Core’s query pipeline

• Understand how LINQ expressions are translated into SQL and where that translation breaks down

• Diagnose and resolve “could not be translated” errors by restructuring logic into SQL-compatible forms (joins, projections, subqueries)

• Optimize generated SQL for performance and correctness

Runtime Metaprogramming

• Implement runtime type generation to support dynamic and evolving data shapes

• Safely generate and cache dynamic types without introducing memory leaks or excessive allocations

• Use reflection and expression compilation strategically to balance flexibility and performance

API & Architecture Design

• Design and implement Fluent APIs and Builder-pattern–based interfaces

• Build expressive, discoverable APIs similar in spirit to EF Core’s Fluent API

• Ensure internal APIs are composable, testable, and difficult to misuse

• Contribute to overall system architecture with an emphasis on extensibility and long-term maintainability

Functional Programming in C#

• Use generics, delegates, and higher-order functions extensively

• Pass behavior as data to enable composability and reuse

• Apply functional patterns where they improve clarity and correctness without sacrificing pragmatism

Required Qualifications

Core Technical Requirements

• Extensive experience with .NET application development

• Advanced LINQ expertise beyond standard query usage

• Expert-level knowledge of System.Linq.Expressions

• Proven experience writing custom ExpressionVisitor implementations

• Deep understanding of Entity Framework Core internals and SQL translation behavior

• Strong knowledge of C# generics, delegates, and functional programming concepts

Architectural & Design Skills

• Strong experience designing internal frameworks or infrastructure components

• Mastery of the Builder Pattern and Fluent API design

• Ability to reason about abstraction boundaries and runtime behavior

• Experience building systems meant to be extended by other developers

Preferred Qualifications

• Experience building ORMs, query providers, or rule engines

• Familiarity with compiler theory or expression-based DSLs

• Performance tuning experience at the .NET runtime and database levels

• Experience mentoring senior developers on advanced C# and EF topics