Thanks for the resources! I managed to get both working in the end. Some notes for future readers: For SDK v3, I just needed to add the forcePathStyle flag. F

Thanks for the resources! I managed to get both working in the end. Some notes for future readers: For SDK v3, I just needed to add the forcePathStyle flag. For aws4fetch (note that this isn't a presigned request, it's just signing the request for Sig V4 like the official SDK would), I needed to change the fetch url to https://my-account-id.r2.cloudflarestorage.com/my-bucket/key https://my-account-id.r2.cloudflarestorage.com/my-bucket/key.