[balac]

Does anyone know of an open source web based SVG editor with Visio compatibility than can be embedded into applications?

[dmgrow]

Lucidchart isn't open source but it does have a public API allowing the editor to be embedded in other applications.

https://www.lucidchart.com/pages/api_documentation

Or it has a simpler Visio API which allows other applications to use Lucidchart as a Visio viewer.