This is a good question: we are going to add this in our FAQ.
Links to png or svg generated by
http://www.plantuml.com/plantuml are valid forever (well, as long as the server is up).
However, we do NOT store any diagrams on our servers.
This may sound contradictory. It is not: the whole diagram is compressed into the URL itself (see
http://plantuml.com/pte )
When the server receives the URL, it decompresses the URL to retrieve the diagram text and generates the image.
There is no need to store anything.
Even if the server is down you can retrieve the diagram using the flag -decodeurl with the command line.
Occasionally we may activate HTTP traces on our server. This is mainly for performance issues (when we have some) to be able to understand what sort of traffic we have on the server. Once the issue solved, we turn back off HTTP traces and we remove the logs.
Note that we are also counting the number of diagrams generated (printed at the home page
http://plantuml.com/ ) to measure general server load.
Concerning sensitive contents, even if we do not store generated diagrams, please be aware that all the traffic goes through HTTP. This means that is it easy to catch it. So you should probably install a local server (
http://plantuml.com/server ) on your own network if you plan to generate diagrams with sensitive information.
Do not hesitate to ask more questions if needed.
