Pinterest cut AI costs 90% by gutting a frontier model's vision layer

At 620 million monthly users, calling a frontier model for every image recommendation isn't a strategy — it's a bill. Pinterest CTO Matt Madrigal solved it by gutting Qwen3-VL's vision layer and rebuilding it with proprietary embeddings, cutting costs 90% and boosting accuracy 30%.Madrigal’s team has been heavily investing in customizing open-source models “foundationally in-house.” “If you've got really unique data that you can then fine-tune an open source model with, data