Why WebP for converted vectors
WebP combines the two properties you usually want from a rasterised SVG on the web: transparency, like PNG, and a much smaller file, typically 25–35 % below an equivalent PNG. Every current browser displays it. The converter rasterises the SVG with resvg in your browser at the size you choose, then encodes WebP using the browser's native encoder — the same one Chrome or Firefox use themselves. Files are never uploaded.
Quality and transparency
The quality slider controls lossy WebP encoding. At 90 and above, artefacts on graphics are effectively invisible while the file is still far smaller than PNG; 80 is a sensible default for large hero images. Transparency is preserved at every quality level, so the default Transparent background is correct for icons and logos. Choose a colour only if the target platform cannot display alpha.
SVG or WebP on your site?
If the platform accepts SVG, an optimised SVG is usually the better asset: it is resolution-independent and often smaller than any raster. Convert to WebP when uploaders reject SVG (social networks, many CMS media libraries, marketplaces), when you need a fixed-size thumbnail, or when the SVG is so complex that rendering it on every page load is slow. Run the SVG Optimizer first in either case; for PNG or JPEG output see SVG to PNG and SVG to JPG.