Top 15 Most Downloaded Python Packages on PyPI and Their Uses

Today we share the Python packages that have received the most downloads on PyPI in the past year, describing what they do, how they relate to each other, and why they are so popular.

1. urllib3 – 893 million downloads

urllib3 is an HTTP client that adds many features missing from the Python standard library, such as thread safety, connection pooling, SSL/TLS verification, multipart file upload, request retry, gzip/deflate support, and proxy handling.

Thread‑safe

Connection pools

SSL/TLS verification

Multipart file upload

Retry and redirect handling

gzip/deflate support

HTTP and SOCKS proxy support

Although its name suggests a successor to urllib2, urllib3 is a separate library; for pure standard‑library usage you may prefer urllib.request . For most users, the higher‑level requests package (listed later) is recommended.

2. six – 732 million downloads

six provides utilities to write code that runs on both Python 2 and Python 3, masking syntax differences (e.g., six.print_() works on both versions). The package name comes from 2 × 3 = 6.

Package name derives from 2 × 3 = 6

Related libraries include future

For converting code to Python 3 only, see 2to3

Python 2 reached end‑of‑life on 1 January 2020, so migration to Python 3 is encouraged.

3. botocore, boto3, s3transfer, awscli

botocore – 660 million downloads (rank 3)

s3transfer – 584 million downloads (rank 7)

awscli – 394 million downloads (rank 17)

boto3 – 329 million downloads (rank 22)

botocore is the low‑level AWS core library; boto3 builds on it to provide a high‑level interface to services like S3 and EC2. awscli uses botocore as its foundation.

s3transfer manages S3 transfers and is a dependency of boto3, awscli and many other projects. The high rankings reflect the widespread use of AWS services.

4. pip – 627 million downloads

pip is the standard Python package installer, allowing easy installation from PyPI or private indexes.

Key points about pip:

Recursive name: "Pip Installs Packages"

Install with pip install <package> , uninstall with pip uninstall <package>

Works well with requirements.txt and virtual environments (e.g., virtualenv )

5. python-dateutil – 617 million downloads

Provides powerful extensions to the standard datetime module, such as fuzzy parsing of dates from log lines.

<code>from dateutil.parser import parse

logline = "INFO 2020-01-01T00:00:01 Happy new year, human."
timestamp = parse(logline, fuzzy=True)
print(timestamp)  # 2020-01-01 00:00:01</code>

6. requests – 611 million downloads

Built on urllib3, requests makes HTTP requests extremely simple.

<code>import requests

r = requests.get("https://api.github.com/user", auth=(user, pass))
print(r.status_code)   # 200
print(r.headers["content-type"])  # application/json; charset=utf8
print(r.text)
print(r.json())</code>

7. s3transfer – 560 million downloads

See entry 3 for details; it is tightly coupled with the AWS libraries.

8. certifi – 552 million downloads

Provides a curated collection of root SSL certificates, allowing Python code to verify HTTPS connections just like browsers do.

9. idna – 527 million downloads

Implements the Internationalised Domain Names in Applications (IDNA) protocol, enabling handling of non‑ASCII domain names in email and HTTP.

<code>import idna
print(idna.encode('ドメイン.テスト'))  # b'xn--eckwd4c7c.xn--zckzah'
print(idna.decode('xn--eckwd4c7c.xn--zckzah'))  # ドメイン.テスト</code>

10. PyYAML – 525 million downloads

YAML parser and emitter for Python, allowing easy reading and writing of YAML files and automatic type conversion.

<code># Using ConfigParser (stores everything as strings)
config.getint("section", "my_int")

# PyYAML automatically preserves types
config["section"]["my_int"]  # returns an int</code>

11. pyasn1 – 512 million downloads

Pure‑Python implementation of ASN.1 types and DER/BER/CER encoding, used by many security‑related libraries (e.g., certifi, RSA).

ASN.1 underlies protocols such as SSL/TLS, SNMP, LDAP, Kerberos, and many others.

12. docutils – 508 million downloads

Modular system for converting plain‑text documents (reStructuredText) to formats like HTML, XML, LaTeX. Used by Sphinx for Python documentation and by many projects on Read the Docs.

13. chardet – 501 million downloads

Detects character encoding of byte streams; often used indirectly by other packages (e.g., requests).

<code>chardetect somefile.txt
# somefile.txt: ascii with confidence 1.0</code>

14. RSA – 492 million downloads

Pure‑Python implementation of the RSA algorithm, supporting encryption/decryption, signing/verification, and PKCS#1 v1.5 key generation.

<code>import rsa
(bob_pub, bob_priv) = rsa.newkeys(512)
crypto = rsa.encrypt('hello Bob!', bob_pub)
message = rsa.decrypt(crypto, bob_priv)
print(message.decode('utf8'))  # hello Bob!</code>

RSA is typically used to encrypt symmetric keys rather than large data payloads.

15. JMESPath – 473 million downloads

Provides a declarative query language for extracting data from JSON structures.

<code>import jmespath

d = {"foo": {"bar": "baz"}}
print(jmespath.search('foo.bar', d))  # baz

# Wildcard example
 d = {"foo": {"bar": [{"name": "one"}, {"name": "two"}]}}
print(jmespath.search('foo.bar[*].name', d))  # ['one', 'two']
</code>

These libraries together illustrate the breadth of the Python ecosystem, from low‑level networking and security to data serialization, configuration, and cloud service integration.