URL: www.inkscape.org

One of the most important tools for a graphics format is a decent drawing program. Inkscape offers state-of-the-art vector drawing, and it's open source.

Moreover, it uses SVG as its native file format. To store Inkscape specific data, it extends the SVG file with elements and attributes in a custom namespace, but you can also choose to export as plain SVG.

URL: www.adobe.com/products/illustrator/

Before Adobe acquired Macromedia, it was the most prominent promoter of SVG. From this time stems the good support of SVG in Illustrator. However, the resulting SVG often shows some quirks, that make it necessary to post-process it for general applicability.

URL: xmlgraphics.apache.org/batik/

Batik is a set of open source tools under the roof of the Apache Software Foundation. The toolkit is written in Java and offers almost complete SVG 1.1 support, as well as some features that were originally planned for SVG 1.2.

Batik offers a viewer (Squiggle), a rasterizer for PNG output, an SVG pretty printer to format SVG files, and a TrueType-to-SVG-Font converter.

Together with Apache FOP Batik can transform SVG to PDF.

Several projects exist that can create a raster image from an SVG source. ImageMagick is one of the most famous command-line image processing tools. The Gnome library rsvg is used by the Wikipedia to raster their SVG graphics. Usage of headless browsers such as SlimerJS and PhantomJS are also popular for this purpose, as the image produced is closer to what the SVG will look like in the browser.

URL: snapsvg.io

A newer JavaScript abstraction layer from the same author of Raphael JS. Snap.svg is designed for modern browsers and therefore supports the newest SVG features like masking, clipping, patterns, full gradients, groups. It does not support the older browsers that Raphael does.

URL: www.google.com/google-d-s/drawings/

Drawings from Google Docs can be exported as SVG.

The well-known plotting tools xfig and gnuplot both support exporting as SVG. To render graphs on the web JSXGraph supports VML, SVG and canvas, automatically deciding which technology to use based on browser capabilities.

In GIS (Geographic Information System) applications SVG is often used as both storage and rendering format. See carto.net for details.

The W3C offers a list of programs that support SVG.