For all italian readers, there is another README written in italian in this repo.
A useful C# helper class to check for the formal validity of any Italian Tax Code / Fiscal Code also known as Codice Fiscale / VAT ID. The code was made by Ryan and released on ryadel.com.
There are many resources online which show how to validate the Fiscal Code, but all these resources use the same approach. The code checks if the fiscal code is valid with an API request to a server which sometimes doesn't work or it uses a big csv file with all the towns in Italy to validate the string. All these features can only work in some situations and the code is not well optimized.
This helper class can perfectly work in every application and it does everything in a single class without using external resources.
The solution has two classes written in english and in italian in order to understand the methods and the parameters used.
The ISTAT Code can be found on dait.interno.gov.it, in the last column on the right named as 'CODICE BELFIORE'.