Memos
Memos is a lightweight note hub for capturing short thoughts, links and reminders without the weight of a full knowledge base. Notes are written in Markdown, tagged for filtering, can carry file attachments, and are exposed through a REST API and webhooks for whatever you want to automate.
People use it as a private scratchpad, a bookmarking feed, a daily journal or a quick channel for sharing updates with a small group, and it can be deployed with sensible defaults.
Because it lives on your own hardware, the notes never leave the building, there is no per-user fee, and the database is trivial to back up and restore.