Log what you do on your computer. Simple (yet powerful), extensible, no third parties.
- There's automatic logging, just like in Recuetime. But unlike Rescuetime, your data is yours as the app is 100% open source, so IMO it is better suited for most corporate privacy policies and hence better for GDPR complience. Rescuetime is fine if you are a home user and don't care about privacy, but due to EU privacy law, it is not suited for the corporate environment in the EU.
- Automatic like RescueTime, but open source and extendable, with full and exclusive user control of data.