What is removed
The minifier removes what isn't needed to show the graphic: comments, metadata, editor data (e.g. of Inkscape or Illustrator), hidden and empty elements, unused definitions and IDs, and whitespace. It also writes numbers, colors, paths and transformations more compactly and merges paths where this doesn't change the look.
If the file can't be made smaller, you get the original file back.
Options
Precision: the number of decimals of coordinates and other numbers (default 3). Fewer decimals make the file smaller; with too few, small details can shift. Compare the preview of the result with the original.
Keep editable: keeps IDs, groups (e.g. Inkscape layers), editor data and metadata. Use it for files you still want to edit, or if scripts or CSS refer to elements by their ID.
Limits
You can upload SVG files of up to 12 MB or paste up to 5 million characters of SVG code. To minify several files at once, upload them as a ZIP (up to 12 MB, with up to 500 SVG files and 100 MB unpacked): you get a ZIP of the minified files back, with the same names and folders.
Used tools
This minifier uses SVGO.