How Buffer uses MongoDB to power its Growth Platform` is a story about how Buffer, a social media management tool, used MongoDB as the foundation for its growth platform. The platform tracks various metrics and events, such as user engagement, API calls, and experiment results, using MongoDB's aggregation framework to make sense of the data. The team uses SQS as a middleman to process tracking data without impacting application performance. They have built client libraries in multiple languages to track events and use ETL jobs to power their growth dashboard. However, they faced challenges such as high disk I/O and write throughput, document limit issues, and reading stale data from secondaries. The team is now working on visualizing results and plans to open-source their growth platform later this year.