Here's a neutral and interesting summary of the text in one paragraph: Pinterest uses Apache Kafka Streams API to provide inflight spend data to thousands of ads servers, reducing overdelivery by building a predictive system that analyzes price, impression rate, and action rate. Overdelivery occurs when free ads are shown to out-of-budget advertisers, reducing opportunities for discovery. The company's system was initially slow to react, leading to extra impressions being shown at no cost, but after implementing the predictive spend pipeline, they significantly reduced overdelivery. By using Apache Kafka Streams API, Pinterest achieved a fast, stable, fault-tolerant, and scalable solution that provides near-instant information about inflight spend, allowing them to respect the budgets of their advertising partners and provide the best experience for advertisers.