Rill Data, a company building the Rill analytics tool, writes about SQL semantic layers, real-time analytics databases and open table formats.
HN commenters mention Rill as a polished, open-source DuckDB-powered BI tool with strong visualizations and pivot tables, in lists of similar products.
The UI aesthetics look similar to the excellent Rill, also powered by DuckDB: https://www.rilldata.com/
Rill has better built in visualizations and pivot tables and overall a polished product with open-source code in Go/Svelte. But the DuckDB UI has very nice Jupyter notebook-style "cells" for editing SQL queries.
There are so many!
Rill Data - https://www.rilldata.com Summer - https://summer.io Hex - https://hex.tech Evidence - https://evidence.dev
This also came to my mind when I heard `rill`, coming from https://www.rilldata.com/ .