I’ve been a fan of using @drawio to create SVG diagrams since early 2016, when I created maps for systems thinking course at Aalto U. in Finland. At that time, draw.io was freeware on many platforms (e.g. saving on Google Drive).
On May 22, 2017, draw.io adopted the Apache 2.0 license, becoming fully open source (with commercial funding from selected open source providers).
In August 2017, desktop versions for Windows, MacOS and Linux were released.
At that time, the pricing for draw.io was reiterated:
- None of our versions are freemium, they are either completely free, or only pay-for.
- You own the content you produce and may use it for any purpose all cases. We don’t sell your personal information or data.
For Dokuwiki, upputtter has a plugin on Github, and there is a 2017-2018 discussion on the Dokuwiki forum.
Any reservations on fully endorsing draw.io as a standards-based, no-charge technology by myself have now been resolved. Download links for draw.io Desktop are on their Integrations page.
In brief. David Ing. 
