LiveStore 
LiveStore is a reactive SQLite-based state management library focused on high-performance client-side reactivity, originally based on Riffle.
LiveStore is under active development by Johannes Schickling.
Electric and Livestore 
ElectricSQL are sponsoring LiveStore development and building a sync integration. This will be released when LiveStore is released (as public open-source code).
Early access 
If you're interested in using LiveStore now, get in touch or contact Johannes directly.