Nibble SVG

Nibble SVG cleans up exported SVG files: it strips editor metadata, merges paths, rounds coordinates and removes hidden layers, typically cutting files by 40 to 70 percent. Unlike most optimizers it shows the original and optimized versions side by side with a pixel diff, so you see if a setting breaks the drawing before you ship it.

It's useful for front-end developers adding icons and illustrations to a codebase, and designers handing off clean assets. It's open source under the MIT license, works offline as an installable web app and processes up to 200 files at once. The caveat: it doesn't optimize embedded raster images inside SVGs.