Using PyMongo with MongoDB Atlas

Atlas is MongoDB, Inc.’s hosted MongoDB as a service offering. To connect to Atlas, pass the connection string provided by Atlas to MongoClient:

client = pymongo.MongoClient(<Atlas connection string>)

Connections to Atlas require TLS/SSL. For connections using TLS/SSL, PyMongo may require third party dependencies as determined by your version of Python. With PyMongo 3.3+, you can install PyMongo 3.3+ and any TLS/SSL-related dependencies using the following pip command:

$ python -m pip install pymongo[tls]

Starting with PyMongo 3.11 this installs PyOpenSSL, requests and service_identity for users of Python versions older than 2.7.9. PyOpenSSL supports SNI for these old Python versions, allowing applictions to connect to Altas free and shared tier instances.

Earlier versions of PyMongo require you to manually install the dependencies. For a list of TLS/SSL-related dependencies, see TLS/SSL and PyMongo.


Connecting to Atlas “Free Tier” or “Shared Cluster” instances requires Server Name Indication (SNI) support. SNI support requires CPython 2.7.9 / PyPy 2.5.1 or newer or PyMongo 3.11+ with PyOpenSSL. To check if your version of Python supports SNI run the following command:

$ python -c "import ssl; print(getattr(ssl, 'HAS_SNI', False))"

You should see “True”.


Industry best practices recommend, and some regulations require, the use of TLS 1.1 or newer. Though no application changes are required for PyMongo to make use of the newest protocols, some operating systems or versions may not provide an OpenSSL version new enough to support them.

Users of macOS older than 10.13 (High Sierra) will need to install Python from, homebrew, macports, or another similar source.

Users of Linux or other non-macOS Unix can check their OpenSSL version like this:

$ openssl version

If the version number is less than 1.0.1 support for TLS 1.1 or newer is not available. Contact your operating system vendor for a solution or upgrade to a newer distribution.

You can check your Python interpreter by installing the requests module and executing the following command:

python -c "import requests; print(requests.get('', verify=False).json()['tls_version'])"

You should see “TLS 1.X” where X is >= 1.

You can read more about TLS versions and their security implications here: