When you create a Spotify application you can see some useful metrics in the app's dashboard. Back in August 2018 I published a screenshot from the dashboard with the data about Spotify Dedup. The usage was steadily increasing, reaching 2.6k monthly users.
That was 1.5 years ago. Since then the UX was improved, dark mode was added, and internationalization was added to include Spanish, German, Portuguese, and French. All of that with huge changes behind the scenes to make the site more maintainable and performant, while keeping it open sourced for anyone to contribute and learn.
The current numbers show that usage has increased till 4.5k users/month, with around 250 daily users:
Note that these are not visitors to the site, but actual users logging in with their Spotify account and analyzing their library.
According to page analytics, around 10% of users browse the site in one of the localized versions, with the Spanish language one being the most used after English.
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