AdCellerant, a growing adtech company, previously used a homegrown authentication solution that became increasingly difficult to manage as the company grew. The application had scaling issues and multiple user data models stored in a MongoDB database, impacting engineering timelines and making it hard to meet client promises. After migrating over 100,000 user attributes to FusionAuth, AdCellerant was able to seamlessly transfer their data without impact to customers and has since used FusionAuth for new projects to drive innovation and growth, including building an API for external developers. The company has praised FusionAuth's responsive support, which has been instrumental in their migration success.