Top 22 Most Downloaded Python Packages on PyPI and Their Uses

Below is a curated list of the 22 Python packages with the highest download counts on PyPI in the last year, together with brief descriptions of their purpose, how they relate to each other, and why they are so widely used.

1. urllib3 (8.93 billion downloads)

urllib3 is a powerful HTTP client that adds 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 pool

Client SSL/TLS verification

Multipart file upload

Retry and redirect handling

gzip/deflate support

HTTP and SOCKS proxy support

Although its name suggests it is a successor to urllib2, urllib3 is a separate library; for pure standard‑library usage see urllib.request . Most end‑users prefer the higher‑level requests library, but urllib3 ranks first because many other packages depend on it.

2. six (7.32 billion downloads)

six provides utilities for writing code compatible with both Python 2 and Python 3, hiding syntax differences such as the print statement/function. The package name comes from 2 × 3 = 6. Related tools include future and the 2to3 conversion script.

3. botocore, boto3, s3transfer, awscli

These four projects are tightly linked:

botocore – 6.6 billion downloads (core AWS SDK)

s3transfer – 5.84 billion downloads (manages S3 transfers)

awscli – 3.94 billion downloads (AWS command‑line interface)

boto3 – 3.29 billion downloads (high‑level AWS SDK)

botocore underpins boto3 and awscli; s3transfer is a dependency of both boto3 and awscli. Their popularity reflects the widespread use of AWS services.

4. pip (6.27 billion downloads)

pip is the standard package installer for Python, allowing effortless installation from PyPI or other indexes. It supports requirements files, virtual environments (via virtualenv ), and dependency resolution.

5. python-dateutil (6.17 billion downloads)

dateutil extends the built‑in datetime module with powerful parsing and timezone handling. Example of fuzzy date parsing:

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)

Built on urllib3, requests simplifies HTTP requests with an intuitive API. Example:

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. s3transfer

See the discussion under package 3 for details.

8. certifi (5.52 billion downloads)

certifi provides a curated collection of root SSL certificates, enabling Python applications to verify HTTPS connections just like modern browsers.

9. idna (5.27 billion downloads)

idna implements the Internationalised 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

10. PyYAML (5.25 billion downloads)

PyYAML parses and emits YAML, a human‑readable data serialization format. Example of loading a YAML file:

import yaml
with open('config.yaml') as f:
    data = yaml.safe_load(f)
print(data)

11. pyasn1 (5.12 billion downloads)

pyasn1 is a pure‑Python implementation of ASN.1 and DER/BER/CER encoding, used in many security‑related protocols (TLS, X.509, SNMP, etc.).

12. docutils (5.08 billion downloads)

docutils converts reStructuredText documents into formats such as HTML, XML, and LaTeX. It powers the Python Enhancement Proposal (PEP) documentation and the Sphinx documentation generator.

13. chardet (5.01 billion downloads)

chardet detects the character encoding of byte streams. Command‑line usage:

chardetect somefile.txt
# ascii with confidence 1.0

14. rsa (4.92 billion downloads)

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

import rsa
(bob_pub, bob_priv) = rsa.newkeys(512)
crypto = rsa.encrypt(b"hello Bob!", bob_pub)
message = rsa.decrypt(crypto, bob_priv)
print(message.decode('utf8'))  # hello Bob!

15. jmespath (4.73 billion downloads)

jmespath 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']

16. setuptools (4.01 billion downloads)

setuptools is the standard tool for building and distributing Python packages. Official documentation is at packaging.python.org .

17. awscli

See package 3 for details.

18. pytz (3.94 billion downloads)

pytz 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

19. futures (3.89 billion downloads)

The futures backport provides the concurrent.futures API for Python 2. Example of a thread pool:

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

20. colorama (3.70 billion downloads)

colorama adds 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")

21. simplejson (3.41 billion downloads)

simplejson is a faster drop‑in replacement for the built‑in json module, with broader Python version support and optional C acceleration.

22. boto3

See package 3 for details.

Conclusion

The most popular packages tend to provide core functionality such as networking, time handling, configuration, encryption, and data serialization, and are often dependencies of many other projects. Understanding these libraries helps developers choose the right tools and avoid unnecessary duplication.