eliteloser/mergecsv

Svendsen Tech's Merge-Csv is a PowerShell function for merging CSV files and/or custom PowerShell objects based on one or more shared ID properties

MergeCsv

Merge-Csv is a function in the MergeCsv module for PowerShell which is now also here on GitHub.

It works well with PowerShell version 3 and up - and might sort of work with PowerShell version 2. PowerShell version 3 or higher is recommended.

Online blog documentation: https://www.powershelladmin.com/wiki/Merge_CSV_files_or_PSObjects_in_PowerShell

It's also published to the PowerShell Gallery: https://www.powershellgallery.com/packages/MergeCsv/

If you have PSv5 or newer (default in Win 10 / Server 2016), you can install with:

Install-Module -Name MergeCsv

or for your user only (elevation not required):

Install-Module -Name MergeCsv -Scope CurrentUser

I will add more information here later, but for now check out the online docs which are comprehensive.

Here's a screenshot demonstrating some of the more sophisticated features.