Distributing Popular Writing Tool For Desktop and Mobile

Objective: Generating new downloads for chrome extension and iOS/Android apps with goal of increasing paid users.


Unique Downloads


Cost Per Download


Upgrade Rate


Grammarly is a browser extension and mobile app which uses AI to help users write more efficiently and without mistakes. It has over 10M downloads on their chrome extension and is one of the most downloaded extensions in the Chrome store.


Grammarly’s goal was to gain new downloads to their free extension and mobile apps with the aim of converting to convert these users into paid plans.

What We Did:

  • We tested all ad networks which were not being tapped into by Grammarly’s own internal marketing team, thus focusing on incremental increases in reach.
  • We tested a mix of contextual, in-app, mobile web and regular display ad units to drive low CPAs and identify sources of high upgrade rates of free users.
  • Our design team created individual creatives to complement each ad network and the context in which the ads appeared, allowing us to split test hundreds of different ads to identify optimal performance.
  • Setup tracking of user retention data on a placement level and used this deeper level information to predict upgrade rates, thus minimizing spend on non-performers.
  • Increased average upgrade rates month over month through continuous optimisation of lower quality placements, creatives and ad networks.
  • Utilised internal anti-fraud technology to prevent fraudulent in-app traffic being driven through three different ad networks.


Despite Grammarly’s internal marketing team having successfully penetrated large ad networks, such as Facebook and Google, we were able to drive incremental volume through numerous smaller ad networks. We were able to cope with this more resource intensive strategy and as a result, we delivered high quality users at the same or lower CPAs than the larger ad networks.

Our Results:

  • We delivered over 194,000 free installs in the first 6 months.
  • We achieved a below target CPA of $18 for upgraded customers
  • Achieved an upgrade rate of 11% of free users to paid users
Prosperys has helped us gain incremental volume of high quality installs and have been a pleasure to work with, very professional and understanding.
Nicki W. Marketing @ Grammarly