C# libraries

Entity Framework Core is Microsoft's official ORM for .NET, translating LINQ queries into SQL with change tracking, migrations and relationship management.

Dapper is a micro-ORM that maps SQL results onto objects with almost no overhead, leaving the SQL entirely under your control.

Serilog is a structured logging library for .NET that treats log events as data with named properties rather than formatted strings.

Polly is a .NET resilience library providing retry, circuit breaker, timeout, bulkhead isolation, rate limiting and fallback as composable policies.

FluentValidation defines validation rules in a strongly-typed fluent API, separate from the model itself.

xUnit.net is the most widely used .NET testing framework, with a minimal API, parallel execution by default and constructor-based test setup.

Moq is the most widely used .NET mocking library, creating test doubles for interfaces and virtual members with a LINQ-based setup syntax.

FluentAssertions provides readable, chainable assertions for .NET with failure messages that explain precisely what differed.

MediatR implements the mediator pattern for .NET, dispatching requests to handlers and decoupling callers from implementations, with a pipeline for cross-cutting behaviour.

AutoMapper maps between object types by convention, removing hand-written property assignments between entities and DTOs.

Json.NET (Newtonsoft.Json) is the long-established JSON library for .NET, with extensive customisation, LINQ to JSON and broad format tolerance.

Autofac is a mature .NET IoC container offering features beyond the built-in one: assembly scanning, decorators, property injection and fine-grained lifetime scopes.

Hangfire runs background jobs in .NET with persistent storage, automatic retries, scheduling and a web dashboard — no separate service required.

MassTransit is a distributed application framework for .NET, abstracting over RabbitMQ, Azure Service Bus, Amazon SQS and Kafka with sagas and routing built in.

Refit turns a C# interface into a REST client, generating the HTTP calls from attributes at build time with no reflection at runtime.

BenchmarkDotNet is a .NET benchmarking library that handles warm-up, statistics, memory measurement and multi-runtime comparison automatically.

Swashbuckle generates OpenAPI documents and a Swagger UI from ASP.NET Core controllers, models and XML documentation comments.

CsvHelper reads and writes CSV files in .NET with class mapping, type conversion and streaming for files larger than memory.

Bogus generates realistic fake data for .NET — names, addresses, emails, dates and text — for tests, seeding and demonstrations.

ImageSharp is a fully managed, cross-platform 2D graphics library for .NET, handling decoding, resizing, format conversion and drawing with no native dependencies.

NSubstitute is a mocking library for .NET with a deliberately minimal syntax, aiming to read as natural language rather than as configuration.

SignalR adds real-time bidirectional communication to ASP.NET Core, negotiating WebSockets where available and falling back automatically.

Quartz.NET is a full-featured job scheduler for .NET with cron triggers, persistent job stores, clustering and misfire handling.

Humanizer converts values into human-readable forms — relative dates, pluralisation, number words, byte sizes and cased strings.

Scrutor adds assembly scanning and decoration to the built-in .NET dependency injection container, without replacing it.

FastEndpoints is a REST API framework for .NET built on minimal APIs, using the REPR pattern — one class per endpoint with its own request and response types.

Mapperly is a source generator that produces object mapping code at compile time, with no reflection and no runtime cost.

NLog is a flexible .NET logging platform with rich routing rules, many targets and configuration that can be changed without recompiling.