Top 20 NuGet attributes Packages

MrAdvice allows to weave aspects at build-time (just like PostSharp, but free as in free beer). Write your own aspects in the form of attributes and apply them to target methods or properties. This version does not require any dependency (on the opposite of MrAdvice.Fody which requires Fody).
Creates and inject attributes and properties to existing types in runtime
Simple OpenApi extensions as attributes
Common functionality for .Net applications - generic repository interface, helper methods for working with attributes, built-in types, etc.
Utilities for projects with base classes, models, interfaces, attributes and useful tools.
Attribute based mapping for NHibernate.
Super-set of MEF attributes. In addition to Export/Import contains attributes to support modern IOC (DryIoc) features.
CompilerAttributes
AngleSharp is the ultimate angle brackets parser library. It parses HTML5, CSS3, and XML to construct a DOM based on the official W3C specification.
Route messages based on Routing Attributes. Includes attributes for Exchange, Queue and Routing.
Contains various basic file functions, functions for working with streams and working with CSV's.
Advanced implementation of the Authentication filter and Authorization attribute for WebApi utilization.
Extensions for configuring Autofac with attributes
Obsolete! Use https://www.nuget.org/packages/MrAdvice/ instead! MrAdvice allows to weave aspects at build-time (just like PostSharp, but free as in free beer). Write your own aspects in the form of attributes and apply them to target methods or properties.
Autofac extension that allows to automatically bind a type with configuration provider through attributes.
Attributes for configuring Autofac registrations
Superset of MEF attributes. In addition to Export/Import contains attributes to support modern IOC (DryIoc) features.
Extension of Enum allowing to retrieve any attributes on any enum values.
Bus Client that is API compatible with 1.x.
Extend objects with attributes at runtime.