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Best way to upload large files to S3

Best way to upload large files to S3

As the world increasingly moves towards cloud-based solutions, the ability to efficiently upload large files to Amazon Simple Storage Service (S3) has become essential for many professionals and organizations. In this detailed how-to guide, I’ll share from personal experience the various methods you can use to tackle this task, including an intuitive method for macOS users through the Commander One app. Whether you’re backing up large datasets, hosting a website with high-resolution media, or simply transferring files between services, mastering the art of uploading large files to S3 can be a game-changer.


Common Scenarios:

Preparing Your Large Files for Upload 📦

  • Ensure your files are eligible for upload, abiding by AWS S3’s size and format restrictions.
  • Pad your filenames appropriately, as Amazon S3 imposes rules about how certain characters are used.
  • Having your AWS credentials at hand is crucial for a smooth upload process.
  • Choose the right tool or application that suits your needs and expertise level.
  • Consider the need for encryption and security during the upload process.

Handling Uploads with Unstable Internet Connections 🌐

  • Use a method that supports resuming uploads, in case the connection drops.
  • Check internet settings to ensure you have the best possible connection for a large file transfer.
  • Select tools or applications that have chunking capabilities which allow splitting the file into parts for upload.

Migrating Large Amounts of Data to S3 ⚙

  • When dealing with a vast amount of data, consider using AWS Data Migration Services or similar.
  • Automate the process with scripts or app features if you are uploading files regularly.
  • If you’re looking for a hands-free approach, AWS S3 Transfer Acceleration can speed up the migration of data over long distances.

Step-by-Step Guide. Uploading Large Files To Amazon S3 Buckets:

Method 1: Using AWS Management Console 🛠

  • Sign in to your AWS Management Console and navigate to the S3 service.
  • Create a new bucket or select an existing one where you want to upload the file.
  • Click on ‘Upload’ and choose the large file from your computer. Note that there’s a 5GB limit for this method.
  • Review your upload details, such as file permissions and storage class, then click ‘Upload’.
  • Monitor the progress in the console until the upload is complete.

Note: This method is straightforward but not recommended for very large files or unreliable internet connections due to the lack of resume capabilities.

Conclusion: The AWS Management Console is suited for occasional uploads of moderately sized files.

Method 2: Using AWS CLI 🖥

  • Install the AWS Command Line Interface (AWS CLI) on your computer.
  • Configure AWS CLI with your credentials using the ‘aws configure’ command.
  • Upload your file using the ‘aws s3 cp’ command, specifying the file path and S3 bucket.
  • For files larger than 5GB, the CLI uses multi-part upload by default.
  • Monitor the CLI output for progress information and any possible errors.

Note: The AWS CLI is a powerful option for those familiar with command-line tools and looking to automate uploads through scripts.

Conclusion: Ideal for automated and larger file uploads, the AWS CLI provides a reliable and scriptable method.

Method 3: Using Amazon S3 Transfer Acceleration ✈

  • Enabled via the AWS Management Console, S3 Transfer Acceleration speeds up the transfer of files over long distances.
  • To use this feature, enable it on your bucket under the bucket properties.
  • Upload files as you normally would, and AWS will route the data through their optimized network paths.

Note: This method incurs additional costs and is ideal when reduced upload times are crucial for large or time-sensitive files.

Conclusion: S3 Transfer Acceleration is valuable for businesses and individuals who need fast uploads across continents.

Method 4: Using S3 Multipart Upload ⚡

  • Consider this method for files larger than 100MB, which splits the file into smaller parts for upload.
  • Several tools and SDKs, like the AWS SDK for Python (boto3), support multi-part uploads.
  • The process includes initiating the upload, uploading the parts, and completing the multi-part upload operation.

Note: Requires programming knowledge or a tool with built-in support for multi-part uploads.

Conclusion: Multipart upload is most effective for very large files and unstable connections, as you can retry individual part uploads.

Method 5: Using Commander One for macOS 🍏

  • Download and install Commander One, an app for macOS that makes managing files between your computer and cloud storage, including Amazon S3, a breeze.
  • Open the app and connect to your Amazon S3 account by adding it as a new connection. You’ll need your AWS access and secret keys here.
  • Navigate to the S3 bucket where you wish to upload your file.
  • Drag and drop the large file from your Mac to the designated S3 bucket in Commander One’s interface.
  • The app automatically manages the upload process, even utilizing multi-part uploads for larger files if necessary.

Note: Commander One offers an intuitive graphical interface that eases the process for users who prefer not to deal with command-line tools.

Conclusion: Commander One is an excellent choice for macOS users looking for a simple and efficient way to handle large file uploads to S3.

Method 6: Using Cloud Storage Browsers 🌥

  • Cloud storage browsers like Cyberduck or Transmit offer an easy-to-use interface for uploading files to Amazon S3.
  • Download and install the application of your choice.
  • Set up your S3 bucket connection by entering your AWS credentials.
  • Navigate to the desired bucket and upload the file using the app’s interface, which frequently includes multi-part upload features.

Note: These browsers can be especially useful for those looking for a balance between a graphical user interface and advanced features.

Conclusion: Perfect for users who prefer a visual approach but also demand robust capabilities like sync and encryption.


Precautions and Tips:

Optimizing Large File Transfers 🚀

  • Compress your files before uploading to save on transfer time and potential costs associated with S3 storage.
  • Use strong network connections to support large data transfers.
  • Monitor the transfer speed and try uploading during off-peak hours if speed is an issue.

Securing Your Data in Transit 🔒

  • Always use encryption options provided by AWS or third-party tools to protect your data during upload.
  • Consider setting up Access Control Lists (ACLs) or bucket policies to manage who can access the uploaded files.

Boosting Cloud Productivity

As someone who has gone through the wringer with uploading large files, I’ve learned that efficiency in cloud file management isn’t just about the upload process itself. Integrating cloud storage solutions into your workflow can significantly enhance productivity across various applications, whether it’s for personal use or across a large team.

For example, plugins and extensions allow users to edit files directly on S3 without the need to download them first, streamlining the revision process. Cloud-based CI/CD pipelines can also deploy large applications directly from S3, saving valuable development time.

For advanced users, consider leveraging AWS Lambda in conjunction with S3 to automate tasks, such as image resizing or data processing, as soon as files are uploaded, triggering what’s called a serverless event-driven architecture.

Ultimately, the ability to upload large files efficiently to S3 opens the door to a myriad of cloud-based optimizations that can transform how you handle data-heavy tasks.


In reviewing these methods and sharing my personal experiences, it’s clear that there isn’t a one-size-fits-all approach to uploading large files to Amazon S3. From the simplicity and graphical user interface of Commander One for macOS to the versatility and automation potential of the AWS CLI, each method comes with its own set of advantages. Your choice will largely depend on factors such as file size, convenience, technical expertise, and your specific use case.

By weighing these factors and taking advantage of tips like file compression, choosing the right time to upload, and ensuring data security, you’re well on your way to mastering the art of large file uploads to Amazon S3.


To upload files over 5GB, you must use multipart upload. This feature allows you to upload the file in smaller, manageable parts.

Amazon recommends using the AWS Command Line Interface (CLI), AWS SDKs, or the S3 Transfer Acceleration for efficient multipart uploads.

Yes, the maximum file size for a single PUT upload is 5TB. For larger files, multipart upload is required.

Yes, if you're using multipart upload. You can resume uploading the remaining parts of the file without re-uploading the completed parts.

If a part fails during a multipart upload, you can re-upload just that part without affecting other already uploaded parts.

Utilize S3 Transfer Acceleration or multi-part upload. Additionally, ensure a stable and high-speed internet connection.

No, you must explicitly choose to use multipart upload. Some high-level abstractions in SDKs and the AWS CLI, however, handle this for you.

While multipart uploads may involve extra requests, they could save costs by enabling you to only re-upload failed parts, not entire large files.

Using AWS SDKs or AWS CLI, you can include progress listeners to notify you about the bytes transferred during the upload process.

Detailed documentation is available on the official AWS Documentation site, which outlines various methods of uploading files to S3. AWS S3 Documentation