# flask > A simple framework for building complex web applications. - **URL**: https://www.freshcrate.ai/projects/flask - **Author**: pypi - **Category**: Frameworks - **Latest version**: `3.1.3` (2026-04-21) - **License**: Unknown - **Source**: https://github.com/pallets/flask/ - **Homepage**: https://pypi.org/project/Flask/ - **Language**: Python - **GitHub**: 71,434 stars, 16,795 forks - **Registry**: pypi (`flask`) - **Tags**: `pypi` ## Description
# Flask Flask is a lightweight [WSGI] web application framework. It is designed to make getting started quick and easy, with the ability to scale up to complex applications. It began as a simple wrapper around [Werkzeug] and [Jinja], and has become one of the most popular Python web application frameworks. Flask offers suggestions, but doesn't enforce any dependencies or project layout. It is up to the developer to choose the tools and libraries they want to use. There are many extensions provided by the community that make adding new functionality easy. [WSGI]: https://wsgi.readthedocs.io/ [Werkzeug]: https://werkzeug.palletsprojects.com/ [Jinja]: https://jinja.palletsprojects.com/ ## A Simple Example ```python # save this as app.py from flask import Flask app = Flask(__name__) @app.route("/") def hello(): return "Hello, World!" ``` ``` $ flask run * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit) ``` ## Donate The Pallets organization develops and supports Flask and the libraries it uses. In order to grow the community of contributors and users, and allow the maintainers to devote more time to the projects, [please donate today]. [please donate today]: https://palletsprojects.com/donate ## Contributing See our [detailed contributing documentation][contrib] for many ways to contribute, including reporting issues, requesting features, asking or answering questions, and making PRs. [contrib]: https://palletsprojects.com/contributing/ ## Recent releases | Version | Date | Urgency | Changes | | --- | --- | --- | --- | | `3.1.3` | 2026-04-21 | Low | Imported from PyPI (3.1.3) | | `3.1.2` | 2025-08-19 | Low | This is the Flask 3.1.2 fix release, which fixes bugs but does not otherwise change behavior and should not result in breaking changes compared to the latest feature release. PyPI: https://pypi.org/project/Flask/3.1.2/ Changes: https://flask.palletsprojects.com/page/changes/#version-3-1-2 Milestone: https://github.com/pallets/flask/milestone/38?closed=1 - `stream_with_context` does not fail inside async views. #5774 - When using `follow_redirects` in the test client, the final state of | | `3.1.1` | 2025-05-13 | Low | This is the Flask 3.1.1 fix release, which fixes bugs but does not otherwise change behavior and should not result in breaking changes compared to the latest feature release. PyPI: https://pypi.org/project/Flask/3.1.1/ Changes: https://flask.palletsprojects.com/en/stable/changes/#version-3-1-1 Milestone https://github.com/pallets/flask/milestone/36?closed=1 - Fix signing key selection order when key rotation is enabled via `SECRET_KEY_FALLBACKS`. GHSA-4grg-w6v8-c28g - Fix type hint for | | `3.1.0` | 2024-11-13 | Low | This is the Flask 3.1.0 feature release. A feature release may include new features, remove previously deprecated code, add new deprecations, or introduce potentially breaking changes. We encourage everyone to upgrade, and to use a tool such as [pip-tools](https://pypi.org/project/pip-tools/) to pin all dependencies and control upgrades. Test with warnings treated as errors to be able to adapt to deprecation warnings early. PyPI: https://pypi.org/project/Flask/3.1.0/ Changes: https://flask.p | | `3.0.3` | 2024-04-07 | Low | This is a fix release for the 3.0.x feature branch. PyPI: https://pypi.org/project/Flask/3.0.3/ Changes: https://flask.palletsprojects.com/en/3.0.x/changes/#version-3-0-3 Milestone: https://github.com/pallets/flask/milestone/35?closed=1 - The default `hashlib.sha1` may not be available in FIPS builds. Don't access it at import time so the developer has time to change the default. #5448 - Don't initialize the `cli` attribute in the sansio scaffold, but rather in the `Flask` concrete | | `3.0.2` | 2024-02-03 | Low | This is a fix release for the 3.0.x feature release branch. It fixes bugs but does not otherwise change behavior and should not result in breaking changes. * Changes: https://flask.palletsprojects.com/en/3.0.x/changes/#version-3.0.2 * Milestone: https://github.com/pallets/flask/milestone/34?closed=1 * PyPI: https://pypi.org/project/Flask/3.0.2/ | | `3.0.1` | 2024-01-18 | Low | This is a fix release for the 3.0.x feature release branch. Fixes an issue where using other JSON providers, such as `flask-orjson`, previously caused loaded session data to have an incorrect format in some cases. * Changes: https://flask.palletsprojects.com/en/3.0.x/changes/#version-3-0-1 * Milestone: https://github.com/pallets/flask/milestone/32?closed=1 * PyPI: https://pypi.org/project/Flask/3.0.1/ | | `3.0.0` | 2023-09-30 | Low | This is a feature release, which includes new features, removes previously deprecated code, and adds new deprecations. The 3.0.x branch is now the supported fix branch, the 2.3.x branch will become a tag marking the end of support for that branch. We encourage everyone to upgrade, and to use a tool such as [pip-tools](https://pypi.org/project/pip-tools/) to pin all dependencies and control upgrades. Test with warnings treated as errors to be able to adapt to deprecation warnings early. * Chan | | `2.3.3` | 2023-08-21 | Low | This is a fix release for the 2.3.x feature branch. - Changes: https://flask.palletsprojects.com/en/2.3.x/changes/#version-2-3-3 - Milestone: https://github.com/pallets/flask/milestone/31?closed=1 | | `2.2.5` | 2023-05-02 | Low | This is a security fix release for the 2.2.x release branch. Note that 2.3.x is the currently supported release branch; please upgrade to the latest version if possible. * Security advisory: https://github.com/pallets/flask/security/advisories/GHSA-m2qf-hxjv-5gpq, CVE-2023-30861 * Changes: https://flask.palletsprojects.com/en/2.2.x/changes/#version-2-2-5 * Milestone: https://github.com/pallets/flask/milestone/30?closed=1 | ## Citation - HTML: https://www.freshcrate.ai/projects/flask - Markdown: https://www.freshcrate.ai/projects/flask.md - Dependencies JSON: https://www.freshcrate.ai/api/projects/flask/deps _Generated by freshcrate.ai. Indexes pypi releases for AI-agent ecosystem packages._