Delivering Large CSV and PDF Exports to Browsers via Object Storage Presigned URLs

The article recommends generating large CSV or PDF exports outside the web request, storing the finished file as an immutable object, and letting browsers download it through short-lived presigned URLs. It argues that the application should manage authorization and export state, while object storage handles the byte transfer and the browser manages resumption. Separating these concerns prevents slow downloads from tying up application workers, rather than simply raising request timeouts. The author stresses that export readiness, URL expiry, and retry behavior must be tracked as distinct states, with retries using stable export identifiers and byte ranges to avoid duplicated work or mixing bytes from different object versions. The piece also notes that the exact validation method depends on the specific storage service and should be tested.