cfgv

Validate configuration and produce human readable error messages.

cfgv Permissive license MIT Active ★ 52 v3.5.0 released 2025-11-19

Install

cfgv on PyPI

pip

pip install cfgv

uv

uv add cfgv

poetry

poetry add cfgv

Package facts

License	MIT (permissive)
Python support	supports the current Python release (>=3.10)
Install friction	low — pure-Python wheel
Runtime dependencies	none
Maintenance	actively maintained — 267 days since the last release
Last repo commit	2026-07-15
First released	2018-02-07
Popularity	one of the top 1,000 most-downloaded packages on PyPI (30-day window, as of 2026-08-13)
Known vulnerabilities	none known (OSV.dev, checked 2026-08-13)

Evidence: cfgv-3.5.0-py2.py3-none-any.whl

Programming Language :: Python :: 3Programming Language :: Python :: 3 :: OnlyProgramming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPy

About cfgv

from the package's own PyPI description — quoted content, verbatim

build status (image) pre-commit.ci status (image)

cfgv

Validate configuration and produce human readable error messages.

Installation

pip install cfgv

Sample error messages

These are easier to see by example. Here's an example where I typo'd true in a pre-commit configuration.

pre_commit.clientlib.InvalidConfigError:
==&gt; File /home/asottile/workspace/pre-commit/.pre-commit-config.yaml
==&gt; At Config()
==&gt; At key: repos
==&gt; At Repository(repo='https://github.com/pre-commit/pre-commit-hooks')
==&gt; At key: hooks
==&gt; At Hook(id='flake8')
==&gt; At key: always_run
=====&gt; Expected bool got str

API

`cfgv.validate(value, schema)`

Perform validation on the schema: - raises ValidationError on failure - returns the value on success (for convenience)

`cfgv.apply_defaults(value, schema)`

Returns a new value which sets all missing optional values to their...

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AI interpretation — verify before relying

AI-generated interpretation of the package facts above; every digit, version, license, or vulnerability id it cites is grounded in the facts already shown on this page

cfgv validates configuration data structures and produces human-readable error messages that pinpoint exactly where validation failed, with support for nested maps, arrays, and conditional validation rules.

Installation is straightforward with no runtime dependencies. The package is actively maintained with a recent release (267 days ago) and clean CI/CD signals.

MIT license permits unrestricted use, modification, and distribution in both open-source and commercial projects without restriction.

Usage

pip install cfgv

import cfgv

schema = cfgv.Map('Config', None, cfgv.Required('key', cfgv.check_string))
cfgv.validate({'key': 'value'}, schema)

Requires Python 3.10 or later.

Verdict: cfgv is a lightweight, well-maintained validation library with zero dependencies, permissive licensing, and no known vulnerabilities. It is suitable for projects needing schema-driven configuration validation with detailed error reporting.

Needs verification

Whether the package is actively used in production by major projects beyond pre-commit ecosystem
Performance characteristics when validating very large or deeply nested configuration structures

configuration validation libraryschema validation with error messagesnested config validationyaml config validatorstructured data validationconfig file schema checkerhuman readable validation errors