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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.
This one is open-source and not bad. It supports tags, which may be what you want. It's not exactly what you're requesting in regards to categories and sub-categories although you could set it up that way. Honestly if you're worried about being productive then you might want to consider if being so meticulous is more hindering than not. It doesn't have a desktop client, but I have found that it's easier to just keep things on your phone. You can save backups as csv files and then sync these with your computer somehow.
NOTE:
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