Top 20 NuGet flat Packages

An ETL framework for .NET
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.
ETL Framework for .NET
JSON extension to Cinchoo ETL framework
Open Source library for automatic formatted file read/write operations www.filehelpers.net
Simple JSON flat file data store
Fixed Width Parser Writer for reading and writing flat data (files) with defined field position in line or file (relative height).
An opensource library written on C#. It contains a lot of useful things.
A library to import and export data from plain text files in a Linq compatible way
FlatFile.Delimited.Attributes is extension for FlatFile.Delimited package for attribute-based mapping
FlatFile is fast-working open-source library for reading/writing plain files
FlatFile.FixedLength.Attributes is extension for FlatFile.FixedLength package for attribute-based mapping
FluentFiles.FixedLength.Attributes is extension for FluentFiles.FixedLength package for attribute-based mapping
FluentFiles.Delimited.Attributes is extension for FluentFiles.Delimited package for attribute-based mapping
FluentFiles is fast-working open-source library for reading/writing plain files
FlatFile.Delimited is fast-working open-source library for delimeted plain files such as cvs and etc.
FlatFile.FixedLength is fast-working open-source library for reading/writing fixed-length plain files
Core library for FlatFile.[name].Attributes assemblies
FluentFiles.FixedLength is fast-working open-source library for reading/writing fixed-length plain files
FluentFiles.Delimited is fast-working open-source library for delimited plain files such as cvs and etc.