What the CSV tool does
It reads UTF-8 CSV files in your browser, matches columns by header, and creates one downloadable CSV. It can add source filenames, remove identical rows, and guard formula-like cells in the export. The preview shows the first five rows; the download includes all rows.
What it does not do
It does not accept XLSX files or guess that differently named columns mean the same thing. It does not send selected file contents to our server. Check the preview before downloading, especially if your exports use inconsistent header names.
Other tools and contact
The site also has Korean-language PDF, Excel, location, and calendar tools. For a problem with this page, email lottolove5131+toolbox@gmail.com. Please describe the issue without attaching sensitive files.