Write and connect a web of your ideas easily and access itreliably. You can use it collect and compound your knowledge at scale.

It's for free for personal use, public and private.

Linked thinking and linked note taking

Exploratory writing

Journaling / diaries

Making a public Digital garden or private Second brain / Zettelkasten

For live editing with a group, such as in a meeting or at an event

Building an Antilibrary

See the Scrapbox Help project

inteltank has created an excellent series of articles introducing Scrapbox (in Japanese, to be translated)