Conversion
Converters
dvisvgm
SvelTeX primarily uses dvisvgm to convert DVI, PDF, and XDV files to SVG. It does so by spawning a child process from which it calls the dvisvgm command.
dvisvgm is bundled with TeX Live and MiKTeX, so if you can compile a LaTeX document, you probably have dvisvgm installed already.
Poppler
Intended as a sort of fallback, SvelTeX can be configured to use Poppler to convert PDF files to SVG. Poppler is then called via the node-poppler package.
Poppler internally uses pdftocairo to convert PDF files to SVG.[1] Poppler and Cairo are also used by pdf2svg, which is another tool that can be used to convert PDF files to SVG (though, to be used with SvelTeX, it'd have to be configured as a custom CLI instruction via the overrideConversion setting).
To be clear, Poppler is a fantastic tool, but it's less specialized than dvisvgm, and doesn't work with DVI or XDV files. This last point is particularly important, since PDF is, compared to DVI or XDV, a lossier intermediate format for the TeX to SVG pipeline in some regards. Furthermore, in my testing, Poppler's SVG output has been consistently larger than dvisvgm's (when the latter is used via DVI/XDV).
See release notes for Poppler 0.17.3 from 2011-08-29. ↩︎