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fivetran

fivetran/great_expectations

Python data quality library that lets teams write declarative Expectations as unit tests for their data and generate validation reports.

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What is it?

GX Core, the open-source core of Great Expectations, is a Python library for validating data quality. Its central concept is the Expectation, a declarative assertion about a dataset such as a column's values falling within a range or a table having no null keys. Teams use these assertions as unit tests for data, running them inside pipelines to catch bad data before it reaches downstream consumers.

Validation results can be turned into automatically generated documentation, so people outside engineering can read what was checked and what passed or failed. The shared vocabulary of Expectations is meant to help data, analytics and engineering teams agree on what good data looks like. The library is installed with pip and started by creating a Data Context with gx.get_context(). It supports Python 3.10 through 3.14.

Key features

  • 01Declarative Expectations that act as unit tests for datasets
  • 02Automatically generated documentation for validation results
  • 03Shared, readable vocabulary for expressing data quality rules
  • 04Installable with pip and started with a single Data Context call

Use cases

  • Validating data in ETL or ELT pipelines before loading into a warehouse
  • Adding data quality checks to machine learning training data pipelines
  • Sharing readable data quality reports with non-engineering stakeholders

Quick start

  1. 1

    Create and activate a Python virtual environment (recommended by GX)

  2. 2

    Install GX Core with pip

    pip install great_expectations
  3. 3

    Import GX and create a Data Context in Python

    import great_expectations as gx context = gx.get_context()

Things to know

  • Requires Python 3.10 to 3.14; newer Python versions have only experimental support.

Topics

FAQ

What is great_expectations?
Python data quality library that lets teams write declarative Expectations as unit tests for their data and generate validation reports. GX Core, the open-source core of Great Expectations, is a Python library for validating data quality. Its central concept is the Expectation, a declarative assertion about a dataset such as a column's values falling within a range or a table having no null keys. Teams use these assertions as unit tests for data, running them inside pipelines to catch bad data before it reaches downstream consumers.
Is great_expectations free to use? What license does it have?
great_expectations is open source under the Apache-2.0 license. Check the license terms before using it in commercial products.
Is great_expectations still maintained?
Actively maintained. The last commit to great_expectations was on Oct 16, 2026.
What can I use great_expectations for?
Validating data in ETL or ELT pipelines before loading into a warehouse Adding data quality checks to machine learning training data pipelines Sharing readable data quality reports with non-engineering stakeholders
How do I install great_expectations?
Create and activate a Python virtual environment (recommended by GX) Install GX Core with pip: pip install great_expectations Import GX and create a Data Context in Python: import great_expectations as gx context = gx.get_context()
Where can I get great_expectations?
The source code and installation instructions are on GitHub: https://github.com/fivetran/great_expectations

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