I only just downloaded this and installed it now, so I haven't had much time to 'play' with this. However, it might be of interest. It sounds similar to "Scapple" - though not in the flowchart style. It's available for the next two or 3 days for free (it's now 4:10am, ET, September 26, 2017). I trust the shareware site, and have not had any problems with malware, etc. in any of their offers. They request your email before you download the 'download' program. The file was only about 5 Mb, and the install ran smoothly. No registration is required - however you need an active internet access in order for it to 'self-register' (done automatically the first time the program is run).
Here is the description page:https://sharewareonsale.com/s/allmynotes-organizer-deluxe-sale
Here is the download page (a small installer file will auto-start):https://sharewareonsale.com/checkout/order-received/9017723?key=wc_order_59ca092fa498d