Scapple is relatively inexpensive (typically around $20 USD) and is a one-time fee rather than a subscription.
A free, hand-drawn style virtual whiteboard that is excellent for quick, unpolished brainstorming sessions. scapple-1-0-keygen
If you want to use Scapple without the risks of pirated software, consider these official options: Scapple is relatively inexpensive (typically around $20 USD)
Web-based collaborative whiteboards that offer free tiers for brainstorming. scapple-1-0-keygen
A powerful note-taking app that includes a "Canvas" feature very similar to Scapple's free-form note-linking.