Bulk Address Excel Generator

I need a small utility—desktop app or compact script—that lets me upload a plain-text file containing anywhere from 100 to 1,000 lines of raw addresses (Name, Street, City, State, Zip). When I hit “process,” it must instantly create an Excel file with the exact columns below, in this order:

Customer_Name | AddressOne | Country | Postal | City | State | Service | Package_Type | Billing | Package_Weight

Country can default to “US.” For Service, Package_Type, Billing, and Package_Weight I will hand you a separate CSV that holds the values I want pre-filled; your program should read that once and apply the same data to every row unless I swap in a new CSV.

Speed is important—I’d like to run the tool right after delivery—so keep setup friction low. A simple Python (pandas / openpyxl) or lightweight .NET executable is fine as long as I can double-click, point to my files, and get the finished spreadsheet.

Acceptance checklist
• Reads my plain-text address file and my CSV of fixed fields without errors
• Generates the Excel sheet in seconds, with columns in the exact sequence above
• Handles at least 1,000 rows in a single pass
• Runs locally on Windows 10/11 without extra paid dependencies

Please package the code, any required libraries, and a brief “how-to” so I can start using it right away.

I want someone who will work on this project instantly