Why did my blank lines disappear before?
The old version treated every blank line as a duplicate of the first blank line, so all but one were removed from the whole document, and that was the default. Now blank lines are kept unless you ask otherwise.
Some switches used to do nothing. Why?
The interface read option names the engine did not have, so the trim and keep-empty switches were wired to nothing and stayed permanently off. Every control is now connected to a real option.
Will my Windows file still be a Windows file?
Yes. CRLF line endings are detected and restored. The old version silently converted everything to LF.
What is the difference between keep first and keep last?
When your matching rule ignores case or spacing, the repeats are not identical, so it decides which text survives. You can also choose whether the survivor sits in the first or the last position.
Why does sorting warn me about keep first?
Sorting replaces the original order, so where a line came from stops mattering. The choice still decides which text survives, just not where it lands.
Alphabetical or natural, which do I want?
Alphabetical is plain A to Z, so item10 comes before item2. Natural reads the digits as numbers, so item2 comes first. The old tool labelled natural sort as alphabetical.
What happens to lines that are not numbers in a numeric sort?
They are grouped at the end and counted in a message. The old version turned them into zero, so text landed silently among your numbers.
Can I dedupe a CSV on one column?
Yes. Choose CSV rows, pick the column, and keep the header out of the comparison. Quoted commas are handled properly, so a field like "Smith, John" is not split.
Does anything leave my browser?
No. Everything runs in this tab, there is no network request in this tool, and it works offline.