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Exist vs Perfice: catalog facts
Exist	Perfice
Paid Subscription service with a free trial.	Free Free and open source under the MIT licence.
Web	Android
Combines automatic syncing with manual tracking Finds correlations between habits and outcomes	Track any custom value, not just preset categories Shows correlations between tracked items
Paid after the trial Relies on connecting third-party services	Correlations need consistent logging over time to be useful Little documentation on the homepage
Web application, Hosted service	Downloadable app
Closed source	Open source
License not stated	License: MIT
Account needed	Not stated if an account is needed
Needs internet	Not stated if it works offline
Official website Full listing and sources Checked October 1, 2026	Official website Full listing and sources Checked October 2, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.