Top 20 NuGet fixed-width Packages

Reads and writes CSV, fixed-length and other flat file formats with a focus on schema definition, configuration and speed. Supports mapping directly between files and classes.
Bulk insert from flat files (csv or fixed length) to sql server table, using datareader to maximize performance and memory usage.
Lightweight .NET class for reading and writing fixed-width data files. Includes basic reader and writer class, and also includes generic classes that automatically map class properties to fixed-width fields. Includes many options to control the library's behavior.
Read flat files using the ADO.NET IDataReader interface. This project has been retired and replaced with FlatFiles, which is easier to use, supports more file formats and is extremely fast!
Use FlatFiles to generate MVC ActionResults.
Library to parse fixed-width data into C# POCO objects
The Software Botany Ivy project is a library containing various string utilities. Included in the library are fluent APIs for parsing and creating delimited and fixed width positional text.