The Filesystem S3 Adapter is a new feature in AWS Lambda that allows users to transfer data into or out of Lambda storage without provisioning a Virtual Machine (VM), reducing time and cost. This adapter enables a subset of the S3 API, including GetObject, PutObject, DeleteObject, and list, allowing users to use familiar S3 APIs directly with their Lambda Filesystem. The feature is designed for AI/ML practitioners and researchers using Lambda Cloud, particularly those using 1-Click Clusters, and offers benefits such as lowest-cost inference, drop-in open-source API replacement, no MLOps required, access to latest open-source models, and custom performance tuning.