SysSimulator is built to be usable without an account. This page summarizes what stays on your device, what can leave it, and what we do not do.
Your canvas and diagram JSON are saved in your browser’s localStorage (on your machine). We do not operate a central “cloud save” for diagrams. Clearing site data or using another browser means that copy of a diagram is gone unless you export JSON, export PNG, or have a share link you copied (see below).
When you choose Copy share link in the simulator, the app POSTs your diagram JSON to a serverless API on the same host (e.g. Vercel). The payload is stored in a database (e.g. Neon Postgres) under a short random code, with an expiry of about seven days, after which it is eligible for deletion. No account is created; we use this so diagrams can be shared without putting large payloads in the URL.
Do not put secrets, credentials, or personal data you would not send in a support ticket into a diagram you upload via share link.
There is no sign-up. We do not ask for your name or email to run the simulator.
If you use the in-app feedback form, your message may be sent to a serverless API (for example to store a ticket or email maintainers). Only submit what you are comfortable sharing. Do not paste secrets, credentials, or personal data you would not put in a support email.
The deployed site may use standard Vercel analytics or similar scripts to measure performance and usage in aggregate. Those tools are governed by the host’s policies.
Questions or privacy concerns: contact the author.