---
id: datadiff
version: "2.2.0"
license: unclear
license_treatment: permissive
maintenance: abandoned
---

# datadiff — DataDiff is a library to provide human-readable diffs of python data structures.

License: permissive · Maintenance: abandoned · Downloads: 101.2K/mo

## What it is and what it does

DataDiff is a utility library that compares Python data structures and outputs the differences in a unified diff format, similar to what you'd see comparing text files. It recursively diffs dictionaries and sequences, and has special handling for multi-line strings. The library also provides drop-in replacements for test assertions (like `assert_equal`) that display a data diff when the assertion fails, making it easier to spot what actually differs in complex nested structures during test failures.

The package has no runtime dependencies and installs cleanly. However, it has been abandoned with no active maintenance, so it should be considered stable but not actively developed. It was originally designed to support Python 2.6 through Python 3, though current compatibility with recent Python versions is untested.

Use it for:

- Debugging test failures by displaying a clear diff of expected vs. actual data structures in assertions
- Comparing complex nested dictionaries or lists to quickly identify which fields or elements changed
- Generating human-readable output when validating API responses or configuration objects in tests
- Inspecting differences in large data structures without manually walking through nested levels

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Generates human-readable diffs of Python data structures (dicts, lists, tuples, sets, strings) and provides drop-in assertion replacements for test frameworks.

Yes, if you need readable diffs for test debugging and don't require active maintenance. The package is stable, has no dependencies, and works for its stated purpose. However, avoid it if you need ongoing support or compatibility assurance with current Python versions.

## Install

pip install datadiff
uv add datadiff
poetry add datadiff

## Installing datadiff

Before you install: Low install friction with no runtime dependencies. Package is abandoned (last release 1083 days ago, status marked abandoned), so no active maintenance or bug fixes should be expected.

License in practice: Licensed under Apache License 2.0 (permissive), so you can use, modify, and distribute freely with minimal restrictions.

Quickstart:

pip install datadiff

from datadiff import diff
a = {'foo': 1, 'bar': 2}
b = {'foo': 1, 'bar': 4}
print(diff(a, b))

Verify before relying:

- Whether the package works reliably on modern Python versions given its abandoned status
- Whether there are known compatibility issues with current testing frameworks or data structures

## Package facts

- License: not declared (permissive)
- Python support: unspecified
- Install friction: low
- Maintenance: abandoned
- Downloads: 101.2K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

python data structure diff, dict list comparison output, test assertion diff display, readable data structure diff, nested data comparison, unified diff for python objects, testing-utilities, data-comparison

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