Dataframely

Judgement

What it is

Building block

What it does

A Python library for declaring schemas and validation rules for Polars DataFrames and checking data against them, with typed DataFrame hints.

Adopt it when

Your data pipelines use Polars and you want declared schemas and rule checks instead of ad hoc asserts.

Watch out

It works only with Polars and is about eighteen months old; Pandera is the more established alternative.

Ready for

Usable

Runs as

Library

Built with

Python, Polars and Rust

How established

Young: started 18 months ago, latest release v3.1.2.

What the license allows

You can build it into a product you sell, as long as you keep its copyright notice.

Judged on 2026-11-06 from the project's README and GitHub data. The license and age lines are worked out directly.

Built from

Follow it down: Dataframely → CPython → GCC → LLVM project → runs on a microchip

How compilers were built, back to punched paper tape

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