moto
A library that allows you to easily mock out tests based on AWS infrastructure
Decision gist · record as of 2026-08-14
Yes. Moto is a mature, actively maintained library in the top 1000 PyPI packages with no known vulnerabilities. It has low install friction, permissive licensing, and solves a real problem: testing AWS-dependent code without infrastructure costs or external dependencies. Install it if you write code that calls boto3.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.10 or later.
- Low friction: pure Python wheel with well-established dependencies (boto3, botocore, cryptography, requests, xmltodict, werkzeug, responses).
- Active maintenance with recent releases and 8613 repository stars.
License · maintenance · safety
Apache-2.0 (permissive) — Apache-2.0 is permissive; you can use this in commercial projects without restriction, though you must include a copy of the license.
last release 2026-06-06 (69 days) · last repo commit 2026-08-11 · 8,613 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 47,377,426 downloads/mo, #600 on PyPI
Alternatives
Verify before relying
pip install moto
import boto3
from moto import mock_aws
@mock_aws
def test_example():
s3 = boto3.client('s3', region_name='us-east-1')
s3.create_bucket(Bucket='test-bucket')
# Test code here- Which AWS services and features are fully mocked versus partially supported or stubbed.
- Whether moto's mocked behavior matches real AWS behavior in edge cases or error conditions.
- Performance overhead of moto's state tracking during large test suites.
What it is and what it does
Moto is a testing library that intercepts boto3 calls and replaces them with in-memory mocks of AWS services. Instead of making real API calls to AWS, your tests run against moto's virtual AWS account, which tracks state (buckets, keys, instances, etc.) in memory. This lets you test AWS-dependent code without credentials, network calls, or AWS charges.
You use it by decorating test functions with @mock_aws or by using it as a context manager. Moto supports multiple AWS services (EC2, S3, and others documented in its implementation coverage guide). The library depends on boto3, botocore, and several HTTP/parsing utilities to intercept and simulate AWS responses.
Use it for
- Unit test code that uploads files to S3 without creating real buckets or incurring storage costs.
- Test EC2 instance lifecycle code (launch, terminate, describe) in isolation without AWS credentials.
- Run CI/CD pipelines that exercise AWS-dependent code without network access or AWS account setup.
- Develop and iterate on AWS integrations locally before deploying to a real environment.
- Test error handling and edge cases in AWS code without risking data or incurring charges.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
Moto is a mature, actively maintained library in the top 1000 PyPI packages with no known vulnerabilities. It has low install friction, permissive licensing, and solves a real problem: testing AWS-dependent code without infrastructure costs or external dependencies. Install it if you write code that calls boto3.
Install
moto on PyPI
Before you install
Low friction: pure Python wheel with well-established dependencies (boto3, botocore, cryptography, requests, xmltodict, werkzeug, responses). Active maintenance with recent releases and 8613 repository stars.
Requires Python 3.10 or later.
License in practice
Apache-2.0 is permissive; you can use this in commercial projects without restriction, though you must include a copy of the license.
Quickstart
pip install moto
import boto3
from moto import mock_aws
@mock_aws
def test_example():
s3 = boto3.client('s3', region_name='us-east-1')
s3.create_bucket(Bucket='test-bucket')
# Test code hereVerify before relying
- Which AWS services and features are fully mocked versus partially supported or stubbed.
- Whether moto's mocked behavior matches real AWS behavior in edge cases or error conditions.
- Performance overhead of moto's state tracking during large test suites.
Package facts
| License | Apache-2.0 permissive |
| Python support | Supports the current Python release >=3.10 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 7 packagesboto3botocorecryptographyrequestsxmltodictwerkzeugresponses |
| Maintenance | Actively maintained 69 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 47,377,426 / month, #600 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Programming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Topic :: Software Development :: Testing |
Evidence: moto-5.2.2-py3-none-any.whl
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