C# WinForms Excel Converter

I need a small Windows desktop utility written in C# WinForms that will take 6-15 source workbooks, run a straightforward round of data cleaning and formatting, and then export each one into our existing Excel template (only a couple of header labels will change, everything else stays the same).

Here’s the workflow I’m after: the form lets me select multiple input files, starts processing, standardises dates, numbers and stray spacing, and finally saves a new workbook for every input file using Template.xlsx as the base. A modest progress bar and a scrolling log pane will make it easy to see what was done.

Feel free to rely on EPPlus, ClosedXML, or plain Microsoft Interop—whichever keeps deployment light and licence-safe. Target framework is flexible as long as it runs on a typical Windows 10 machine without extra installs.

Deliverables
• Complete Visual Studio solution with C# WinForms code, clearly commented
• Compiled .exe ready to run
• A brief README that lists prerequisites, the specific cleaning rules you implemented, and where the template edits can be tweaked

Acceptance test: I’ll run ten mixed-quality files through the tool; if every output workbook opens without warnings and mirrors the template’s structure (with the cleaned data in place), the milestone is approved.