Guides & Tutorials

Why These Guides Exist

Merging files sounds like it should take one click, and when the files are identical it does. The guides below deal with the far more common case where they are not. Column headers drift between exports because two teams named the same field differently. A CSV arrives semicolon-separated because it was saved by Excel in a locale where the comma is a decimal separator. A workbook holds a summary tab whose subtotal rows would quietly double every figure if they were merged in.

Each guide covers one of those situations in enough depth to actually solve it, including how to tell that it has happened, what the fix is, and how to verify the merged output afterwards. They are written for the person who has the files open right now and needs the answer, not as an introduction to what a spreadsheet is.

Where to Start

If your merge produced columns that are half empty, start with the Excel or CSV guide depending on your source format; the cause is almost always header mismatch and both guides cover the mapping workflow. If accented characters came out garbled, the CSV guide’s encoding section is the relevant one. If the browser became unresponsive partway through, the large dataset guide explains where the memory limits actually sit and how to work below them.

If you are evaluating whether a browser-based tool is appropriate for confidential data at all, read the data security guide first. It explains what local processing does and does not protect against, and includes a test you can run in under a minute to verify the claim for yourself rather than taking anyone’s word for it.