What does it do?
attrs takes the tedious, repetitive parts of defining a Python class, writing methods to compare two objects, print them nicely, or initialize their fields, and generates all of that boilerplate automatically from a short description you provide. It’s like ordering a custom cake by describing the flavors and size you want, rather than baking every layer from scratch each time. You list the properties an object should have, and attrs fills in all the standard machinery around them. The result is class definitions that are dramatically shorter and less error-prone than writing everything by hand.
See it in action
This defines a simple “point” object with an x and y position, and the library automatically fills in the usual behind-the-scenes setup and printing behavior for it.
import attr
@attr.s
class Point:
x = attr.ib()
y = attr.ib()
p = Point(1, 2)
print(p)Why would a non-developer care?
Less code means fewer places for a typo or copy-paste mistake to hide, and it’s a big part of why some of Python’s most reliable tools feel more predictable than average software. It’s not something you’d notice as a user, but the developers building the tools you rely on notice the difference every day.
Real-world examples
attrs has been used for years across major Python projects that value clean, dependable code, and its ideas were influential enough that Python’s own standard library eventually added a built-in feature called dataclasses that does something similar. That’s a rare honor: a third-party library shaping a core feature of the programming language itself.
Who uses it
Python developers who write a lot of custom data-holding classes and want to avoid retyping the same setup code repeatedly.
How it compares to alternatives
It predates and directly inspired Python’s built-in dataclasses module, and still offers more features and flexibility than the built-in version, like extra validation options. Compared to Pydantic, attrs focuses purely on reducing class boilerplate rather than validating data from external sources.
Fun fact
attrs was created by Hynek Schlawack partly out of frustration with how much repetitive code plain Python classes required, and its success directly shaped the design of dataclasses in Python 3.7.