---
id: flex
version: "6.14.1"
license: BSD
license_treatment: permissive
maintenance: abandoned
---

# flex — Swagger Schema validation.

License: permissive · Maintenance: abandoned · Downloads: 92.8K/mo

## What it is and what it does

Flex is a validation tool for Swagger 2.0 API specifications. It validates swagger schemas themselves, performs JSON Schema validation, and checks request and response objects against their declared schemas. It includes both a Python library and a command-line interface (swagger-flex as of version 5.0.0).

The package is no longer maintained—the last release was in 2019-09-14 and the last repository commit in 2022-09-22. It was originally designed for Python 2.7 and early Python 3 versions (3.3, 3.4, 3.5, 3.6), and its compatibility with modern Python is unknown. High installation friction (source build required) combined with abandonment makes it a risky choice for new projects unless you are locked into Swagger 2.0 validation and cannot use maintained alternatives.

Use it for:

- Validate a Swagger 2.0 specification file before deploying an API to ensure schema correctness.
- Test that API request and response payloads conform to their declared Swagger schema during development.
- Integrate Swagger validation into a legacy CI/CD pipeline that cannot be updated to OpenAPI 3.x tooling.
- Command-line validation of Swagger specs in build scripts using the swagger-flex CLI.

## Worth the install?

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

Validates Swagger 2.0 API specifications against JSON Schema and checks request/response objects for conformance, with a command-line interface.

No. The package is abandoned (last release 2019-09-14, last commit 2022-09-22) with high install friction and uncertain compatibility with modern Python. Swagger 2.0 itself is superseded by OpenAPI 3.x. Use only if forced to validate legacy Swagger 2.0 specs with no alternative; otherwise migrate to a maintained OpenAPI validator.

## Install

pip install flex
uv add flex
poetry add flex

## Installing flex

Before you install: Installation requires building from source (high friction). The package is abandoned—last release was 2019-09-14, last commit 2022-09-22, with no active maintenance. Use only if you are locked into Swagger 2.0 validation and cannot migrate to maintained alternatives.

License in practice: BSD license is permissive and poses no restrictions on use, modification, or distribution in commercial or private projects.

Quickstart:

pip install flex==6.14.1

from flex.core import validate
validate(swagger_spec_dict)

Package targets Python 2.7 and 3.3–3.6; compatibility with modern Python versions is unverified and likely broken.

Verify before relying:

- Whether the package actually works on Python versions beyond 3.6 despite classifier claims.
- Current state of dependencies and whether they have known security issues or are themselves abandoned.
- Whether Swagger 2.0 validation is still the right choice versus migrating to OpenAPI 3.x tooling.

## Package facts

- License: BSD (permissive)
- Python support: unspecified
- Install friction: high
- Maintenance: abandoned
- Downloads: 92.8K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

swagger 2.0 validation, openapi schema validator, rest api specification checker, json schema validation, swagger spec compliance, api contract testing, swagger cli tool, swagger-validation, legacy-api-tooling

[View on SkillFed](https://skillfed.io/packages/flex) · [View on PyPI](https://pypi.org/project/flex/)