Convert tabs to spaces (and back)

Tabs and spaces: the argument you do not have to win

Whether to indent with tabs or with spaces is a long-running debate among programmers, but in practice the problem is usually that a file contains the wrong one for the place where it is going. A project may require spaces, a Makefile requires tabs, a YAML file forbids tabs for indentation, a forum post needs spaces to keep the alignment, and a text pasted between editors can end up with a jumble of both. This tool converts a text from one convention to the other.

Tabs into spaces

Every tab character is replaced by the number of spaces you choose: 2, 4 and 8 are the usual values. This simple rule has one limit that is worth knowing: a real tab jumps to the next tab stop, so its width depends on where it sits in the line, whereas this tool substitutes a fixed number of spaces. For indentation at the start of a line the result is exactly what you want. For tabs in the middle of a line, used to align columns, the alignment may change.

Only the indentation

The option "only the tabs at the start of a line" converts the indentation and leaves tabs inside the line untouched. That is the safer choice for code and for tab-separated data, where tabs in the middle of a line separate columns and must not become spaces.

Spaces into tabs

The opposite conversion turns the spaces that begin a line into tabs, one tab for each group of the chosen number of spaces. A line indented with eight spaces becomes two tabs when the width is four. Leftover spaces that do not fill a group are kept as spaces, so no alignment is lost, and spaces in the middle of a line are never touched.

What it does not do

The tool does not detect the indentation style of your file, does not reformat code and cannot tell whether a tab is inside a string or a comment. For code with strict layout rules, such as Python or YAML, check that the structure is still valid after converting.