s3transfer
An Amazon S3 Transfer Manager
Decision gist · record as of 2026-08-14
Yes, if you need direct control over S3 transfer mechanics and are comfortable with Alpha-stage code. The library is actively maintained by AWS, has no known vulnerabilities, and installs with minimal friction. However, if you are building production systems, either pin to a specific minor version or use boto3's stable S3 interface instead, as the maintainers explicitly warn that interfaces may break between minor releases.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.10 or later; botocore must be configured with valid AWS credentials (via environment variables, config file, or IAM role).
- Low friction: pure Python wheel with a single runtime dependency on botocore.
- Actively maintained by AWS with a recent release; however, the package is marked Alpha and the maintainers explicitly warn that interfaces may break between minor versions, so production use requires pinning to a specific minor version.
License · maintenance · safety
Apache License 2.0 (permissive) — Apache License 2.0 is permissive and imposes no significant restrictions on use or distribution; you may use this in proprietary code without obligation to share modifications.
last release 2026-07-22 (23 days) · last repo commit 2026-07-30 · 237 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 924,268,948 downloads/mo, #29 on PyPI
Alternatives
Verify before relying
pip install s3transfer
from s3transfer.manager import TransferManager
from botocore.session import Session
session = Session()
client = session.create_client('s3')
manager = TransferManager(client)
manager.upload('local_file.txt', 'bucket-name', 'key')- Whether the Alpha stability warning applies to the current 0.19.2 release or is historical guidance.
- Specific performance characteristics (throughput, concurrency limits) for typical workloads.
- Whether s3transfer or boto3's built-in S3 transfer interface is recommended for new projects.
What it is and what it does
s3transfer is a Python library for managing transfers to and from Amazon S3, maintained by AWS. It provides a TransferManager interface that handles the mechanics of concurrent multipart uploads and downloads, retries, and bandwidth control—operations that would otherwise require substantial boilerplate when using botocore directly. The library depends only on botocore and is distributed as a pure Python wheel, making it straightforward to install.
The package is currently in Alpha status, meaning its public API may change between minor releases. The maintainers recommend that production code either pin to a specific minor version or use the stable S3 transfer interface exposed through boto3 instead. It supports Python 3.10 through 3.14 and has been actively maintained, with a release within the last month.
Use it for
- Uploading or downloading large files to S3 with automatic multipart handling and retry logic.
- Performing bulk S3 operations (many files) with concurrent transfers and bandwidth throttling.
- Building custom S3 workflows that need lower-level control than boto3's high-level API provides.
- Integrating S3 transfers into applications where botocore is already a dependency.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes, if you need direct control over S3 transfer mechanics and are comfortable with Alpha-stage code.
The library is actively maintained by AWS, has no known vulnerabilities, and installs with minimal friction. However, if you are building production systems, either pin to a specific minor version or use boto3's stable S3 interface instead, as the maintainers explicitly warn that interfaces may break between minor releases.
Install
s3transfer on PyPI
Before you install
Low friction: pure Python wheel with a single runtime dependency on botocore. Actively maintained by AWS with a recent release; however, the package is marked Alpha and the maintainers explicitly warn that interfaces may break between minor versions, so production use requires pinning to a specific minor version.
Requires Python 3.10 or later; botocore must be configured with valid AWS credentials (via environment variables, config file, or IAM role).
License in practice
Apache License 2.0 is permissive and imposes no significant restrictions on use or distribution; you may use this in proprietary code without obligation to share modifications.
Quickstart
pip install s3transfer
from s3transfer.manager import TransferManager
from botocore.session import Session
session = Session()
client = session.create_client('s3')
manager = TransferManager(client)
manager.upload('local_file.txt', 'bucket-name', 'key')Verify before relying
- Whether the Alpha stability warning applies to the current 0.19.2 release or is historical guidance.
- Specific performance characteristics (throughput, concurrency limits) for typical workloads.
- Whether s3transfer or boto3's built-in S3 transfer interface is recommended for new projects.
Package facts
| License | Apache License 2.0 permissive |
| Python support | Supports the current Python release >=3.10 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 1 packagebotocore |
| Maintenance | Actively maintained 23 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 924,268,948 / month, #29 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 3 - AlphaIntended Audience :: DevelopersLicense :: OSI Approved :: Apache Software LicenseNatural Language :: EnglishProgramming Language :: PythonProgramming Language :: Python :: 3Programming Language :: Python :: 3 :: OnlyProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: Free Threading :: 2 - Beta |
Evidence: s3transfer-0.19.2-py3-none-any.whl
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