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InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
https://github.com/dotnet-presentations/blazor-workshop/blob/main/docs/09-progressive-web-app.md tells you how to implement push notifications the way I think you mean.
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