# Flask-CORS Documentation
# Source: https://flask-cors.readthedocs.io/en/latest/
# Path: index

Flask-Cors

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  * [Configuration](configuration.html)
  * [API Docs](api.html)

__Flask-Cors

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# Flask-CORS¶

[![Build Status](https://api.travis-ci.org/corydolphin/flask-
cors.svg?branch=master)](https://travis-ci.org/corydolphin/flask-cors)
[![Latest Version](https://img.shields.io/pypi/v/Flask-
Cors.svg)](https://pypi.python.org/pypi/Flask-Cors/) [![Supported Python
versions](https://img.shields.io/pypi/pyversions/Flask-
Cors.svg)](https://img.shields.io/pypi/pyversions/Flask-Cors.svg)
[![License](http://img.shields.io/:license-mit-
blue.svg)](https://pypi.python.org/pypi/Flask-Cors/)

A Flask extension for handling Cross Origin Resource Sharing (CORS), making
cross-origin AJAX possible.

This package has a simple philosophy: when you want to enable CORS, you wish
to enable it for all use cases on a domain. This means no mucking around with
different allowed headers, methods, etc.

By default, submission of cookies across domains is disabled due to the
security implications. Please see the documentation for how to enable
credential’ed requests, and please make sure you add some sort of
[CSRF](http://en.wikipedia.org/wiki/Cross-site_request_forgery) protection
before doing so!

## Installation¶

Install the extension with using pip, or easy_install.

    
    
    $ pip install -U flask-cors
    

## Usage¶

This package exposes a Flask extension which by default enables CORS support
on all routes, for all origins and methods. It allows parameterization of all
CORS headers on a per-resource level. The package also contains a decorator,
for those who prefer this approach.

### Simple Usage¶

In the simplest case, initialize the Flask-Cors extension with default
arguments in order to allow CORS for all domains on all routes. See the full
list of options in the [documentation](https://flask-
cors.corydolphin.com/en/latest/api.html#extension).

    
    
    from flask import Flask
    from flask_cors import CORS
    
    app = Flask(__name__)
    CORS(app)
    
    @app.route("/")
    def helloWorld():
      return "Hello, cross-origin-world!"
    

#### Resource specific CORS¶

Alternatively, you can specify CORS options on a resource and origin level of
granularity by passing a dictionary as the resources option, mapping paths to
a set of options. See the full list of options in the
[documentation](https://flask-
cors.corydolphin.com/en/latest/api.html#extension).

    
    
    app = Flask(__name__)
    cors = CORS(app, resources={r"/api/*": {"origins": "*"}})
    
    @app.route("/api/v1/users")
    def list_users():
      return "user example"
    

#### Route specific CORS via decorator¶

This extension also exposes a simple decorator to decorate flask routes with.
Simply add `@cross_origin()` below a call to Flask’s `@app.route(..)` to allow
CORS on a given route. See the full list of options in the [decorator
documentation](https://flask-
cors.corydolphin.com/en/latest/api.html#decorator).

    
    
    @app.route("/")
    @cross_origin()
    def helloWorld():
      return "Hello, cross-origin-world!"
    

## Documentation¶

For a full list of options, please see the full [documentation](https://flask-
cors.corydolphin.com/en/latest/api.html)

## Troubleshooting¶

If things aren’t working as you expect, enable logging to help understand what
is going on under the hood, and why.

    
    
    logging.getLogger('flask_cors').level = logging.DEBUG
    

## Tests¶

A simple set of tests is included in `test/`. To run, install nose, and simply
invoke `nosetests` or `python setup.py test` to exercise the tests.

## Contributing¶

Questions, comments or improvements? Please create an issue on
[Github](https://github.com/corydolphin/flask-cors), tweet at
[@corydolphin](https://twitter.com/corydolphin) or send me an email. I do my
best to include every contribution proposed in any way that I can.

## Credits¶

This Flask extension is based upon the [Decorator for the HTTP Access
Control](https://web.archive.org/web/20190128010149/http://flask.pocoo.org/snippets/56/)
written by Armin Ronacher.

[Next ](configuration.html "Configuration")

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