What Are the 22 Most Popular Python Packages and Why They Matter

Introduction

Curious about which Python packages dominate the ecosystem? I compiled a list of the 22 most‑downloaded packages on PyPI over the past year to highlight their purposes, relationships, and why they are so popular.

1. urllib3

8.93 billion downloads – urllib3 is an HTTP client that adds features missing from the standard library, such as thread safety, connection pooling, SSL/TLS verification, multipart file upload, automatic retries, gzip/deflate support, and proxy handling.

Thread safety

Connection pool

Client SSL/TLS verification

Multipart file upload

Retry and redirect helpers

gzip and deflate support

HTTP and SOCKS proxy support

For most end‑users, the requests library is recommended, but urllib3 ranks first because many other packages depend on it.

2. six

7.32 billion 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 name comes from 2 × 3 = 6

Similar libraries include future For pure Python 3 migration, use

2to3

3. botocore, boto3, s3transfer, awscli

These AWS‑related packages together illustrate the popularity of Amazon services. botocore is the low‑level core used by boto3, which provides Python APIs for S3, EC2, and other AWS services. s3transfer handles S3 transfers and is heavily depended upon by many projects.

4. pip

6.27 billion downloads – pip is the standard package installer for Python, allowing easy installation from PyPI or custom repositories. It supports requirements files, virtual environments, and can install a wide range of packages.

Recursive name: "Pip Installs Packages"

Simple install command: pip install <package> Can uninstall with pip uninstall <package> Works with requirements.txt for reproducible environments

5. python-dateutil

6.17 billion downloads – extends the standard datetime module with powerful parsing and manipulation capabilities.

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

6. requests

6.11 billion downloads – a user‑friendly HTTP library built on top of urllib3.

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())

7. certifi

5.52 billion downloads – provides a curated collection of root SSL certificates, enabling Python code to verify HTTPS connections just like modern browsers.

8. idna

5.27 billion downloads – implements the Internationalized Domain Names in Applications (IDNA) protocol, converting Unicode domain names to ASCII (Punycode) and back.

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

9. PyYAML

5.25 billion downloads – a YAML parser and emitter for Python, allowing easy reading and writing of configuration files with rich data types.

import yaml
config = yaml.safe_load(open('config.yaml'))
print(config['section']['my_int'])

10. pyasn1

5.12 billion downloads – pure‑Python implementation of ASN.1 and DER/BER/CER encoding, used by many security‑related libraries.

11. docutils

5.08 billion downloads – a modular system for converting plain‑text documentation (reStructuredText) into formats like HTML, XML, and LaTeX. It powers tools such as Sphinx and Read the Docs.

12. chardet

5.01 billion downloads – detects the character encoding of text data, useful for processing unknown files or network streams.

chardetect somefile.txt
# Output: ascii with confidence 1.0

13. rsa

4.92 billion downloads – pure‑Python implementation of the RSA algorithm, supporting encryption, decryption, signing, and key generation.

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!

14. jmespath

4.73 billion downloads – provides a declarative query language for extracting data from JSON structures.

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

d = {'foo': {'bar': [{'name': 'one'}, {'name': 'two'}]}}
print(jmespath.search('foo.bar[*].name', d))  # ['one', 'two']

15. setuptools

4.01 billion downloads – the standard tool for building and distributing Python packages.

16. awscli

3.94 billion downloads – the official command‑line interface for AWS services, built on top of botocore and boto3.

17. pytz

3.94 billion downloads – provides accurate and cross‑platform timezone definitions.

from datetime import datetime
from pytz import timezone
amsterdam = timezone('Europe/Amsterdam')
ams_time = amsterdam.localize(datetime(2002,10,27,6,0,0))
print(ams_time)  # 2002-10-27 06:00:00+01:00

18. futures

3.89 billion downloads – backport of the concurrent.futures module for Python 2, enabling easy asynchronous execution with thread pools.

from concurrent.futures import ThreadPoolExecutor
from time import sleep

def return_after_5_secs(message):
    sleep(5)
    return message

pool = ThreadPoolExecutor(3)
future = pool.submit(return_after_5_secs, 'Hello world')
print(future.done())  # False
sleep(5)
print(future.done())  # True
print(future.result())  # Hello world

19. colorama

3.70 billion downloads – enables cross‑platform colored terminal text.

from colorama import Fore, Back, Style
print(Fore.RED + 'some red text')
print(Back.GREEN + 'and with a green background')
print(Style.DIM + 'and in dim text')
print(Style.RESET_ALL)
print('back to normal now')

20. simplejson

3.41 billion downloads – a fast JSON encoder/decoder with optional C acceleration, offering better performance and compatibility across Python versions.

Runs on more Python versions

Frequent updates

Partial C implementation for speed

21. boto3

3.29 billion downloads – the official AWS SDK for Python, built on top of botocore.

Conclusion

Most top‑ranked packages provide core functionality such as networking, configuration, encryption, and data handling, and are widely depended upon by other projects. Understanding these utilities helps developers choose reliable tools and avoid reinventing the wheel.