Tabs to spaces

Why a TAB causes trouble

The tab character is not a width: it's a jump to the next column, and how wide that column is gets decided by whatever program is showing the text. Your editor may draw it 4 wide, the terminal 8, a website's comment box swallows it entirely and another editor shows it 2 wide. That's why the same text, perfectly aligned on your screen, arrives at the other end as a staircase or all bunched up.

What this page does

Every tab becomes four spaces, which is the most widespread size and the one prescribed by Python's official style guide (PEP 8). From that moment the text looks the same everywhere, because a space is a space anywhere. Nothing else is touched: lines, accents, punctuation and special characters stay identical.

The case where it does NOT help

If you copied a table out of Excel or Google Sheets, the columns are separated by one TAB each and the values have different lengths: replacing every tab with four spaces means the columns will not stay aligned, because what kept them in line was precisely the jump to the next column. In that case this page isn't what you need: you need to paste the data into a real spreadsheet, and to do it properly there is CSV to Excel.

Nearby tools

If your problem is instead double spaces and lines ending with one space too many, there is Remove extra spaces; to strip the indent at the start of every line, Remove indents. To replace anything else, tabs included, the general road is Find and replace.