Digital Brain provides various tools for online brainstorming, including tables, drawings and notes – on desktop browsers only.
At this time there is no save feature, so this is for short-term brainstorming.
It’s completely free and available at https://fonte.me/digitalbrain/
Chart City is an experimental, simple charting environment that visualizes tabular data in a variety of chart types. It resides at https://fonte.me/chartcity/
You can either paste data in from Excel or other spreadsheet programs, or type it in manually in a small table on the site. For some charts you need to label the columns.