NASS (Net App Satisfaction Score) is a net satisfaction score published monthly by MWM for companies that publish apps. It is the share of 5-star ratings minus the share of 1-to-3-star ratings, on a scale from −100 to +100, calculated from the ratings and written reviews a company’s apps received on the App Store during the month. It describes the users who rate, not every user.
How NASS is calculated
- Ratings of the month: the difference between the App Store rating counts at the end of the month and at the end of the previous month, star by star and storefront by storefront.
- Two channels: ratings without a review are the ratings of the month minus the written reviews of the month, so no rating is counted twice.
- Score of a channel: share of 5-star ratings minus share of 1-to-3-star ratings. 4 stars are neutral.
- NASS: half the score of ratings without a review plus half the score of written reviews.
- Precision: every NASS comes with a 90% confidence interval; companies whose interval is too wide are not ranked. The interval measures statistical precision only, not who chooses to rate.
Why two channels
Most App Store ratings are left without text, often when the app asks for one at a moment the developer chooses: they lean positive. Written reviews take effort and are more often written by users who have a problem: they lean negative. In August 2026, ranked companies averaged +72.9 on ratings without a review and +25.6 on written reviews. Weighting both channels equally limits the weight of solicited ratings without cancelling either bias, and both sub-scores are published.
NASS and NPS
The idea is close to the NPS, the share of promoters minus the share of detractors, but NASS does not rely on a survey or a recommendation question. It reads the stars users actually left, which makes it reproducible by anyone from public App Store data.
Scope
Version 1 covers iOS apps, games excluded, worldwide and in the United States, with a monthly series starting in January 2025. A company is its operating perimeter: all its App Store accounts combined.