Golang Download S3 File !!top!! May 2026

package main import ( "context" "io" "log" "os" "://github.com" "://github.com" "://github.com" ) func main() { // Load AWS configuration cfg, err := config.LoadDefaultConfig(context.TODO(), config.WithRegion("us-east-1")) if err != nil { log.Fatalf("unable to load SDK config, %v", err) } client := s3.NewFromConfig(cfg) // Get object from S3 result, err := client.GetObject(context.TODO(), &s3.GetObjectInput{ Bucket: aws.String("your-bucket-name"), Key: aws.String("your-file-key.txt"), }) if err != nil { log.Fatalf("failed to get object, %v", err) } defer result.Body.Close() // Create local file file, err := os.Create("downloaded_file.txt") if err != nil { log.Fatalf("failed to create file, %v", err) } defer file.Close() // Stream data from S3 response body to local file _, err = io.Copy(file, result.Body) if err != nil { log.Fatalf("failed to copy object, %v", err) } } Use code with caution. Method 2: High-Performance Concurrent Downloads

It uses io.WriterAt , allowing it to write different parts of the file simultaneously.

Use this method when you need to stream data directly (e.g., to a web response) without saving the entire file to disk first. golang download s3 file

For large files, the is superior. It automatically splits files into chunks and downloads them in parallel using multiple goroutines.

go get github.com/aws/aws-sdk-go-v2 go get ://github.com go get ://github.com go get ://github.com Use code with caution. Method 1: Low-Level Streaming with GetObject package main import ( "context" "io" "log" "os" "://github

If downloading hundreds of files, consider using worker pools or the DownloadObjectsIterator to manage resources efficiently.

Ensure your application is running in the same AWS region as your S3 bucket to minimize latency and data transfer costs. For large files, the is superior

import ( "context" "os" "://github.com" "://github.com" ) func downloadLargeFile(client *s3.Client, bucket, key, destPath string) error { file, err := os.Create(destPath) if err != nil { return err } defer file.Close() // Create a downloader with custom options downloader := manager.NewDownloader(client, func(d *manager.Downloader) { d.PartSize = 64 * 1024 * 1024 // 64MB chunks d.Concurrency = 5 // 5 concurrent goroutines }) _, err = downloader.Download(context.TODO(), file, &s3.GetObjectInput{ Bucket: aws.String(bucket), Key: aws.String(key), }) return err } Use code with caution. Key Comparison: Which one to use? s3.GetObject manager.Downloader Streaming, small files, web responses Large files, high-throughput downloads Interface io.ReadCloser (Sequential) io.WriterAt (Concurrent) Memory Low (Streams data) Moderate (Buffers chunks) Speed Fast (Parallelization) Common Performance Tips