Production version

Recommended install with all features (Redis cache + S3 storage + SVG if py3.4+):

pip install flask-resize[full]

Other alternatives:

# File-based storage only
pip install flask-resize

# With S3 storage support
pip install flask-resize[s3]

# With Redis caching
pip install flask-resize[redis]

# With SVG source file support (only available with py3.4+)
pip install flask-resize[svg]

# Or any combination of above. E.g:
pip install flask-resize[s3,redis]

Development version

pip install -e git+


Tested with Python 2.7/3.4/3.5/3.6/pypy and latest version of Flask.

Should work well on most Linux and MacOS versions.

Windows is supported on paper with the full test suite running smoothly, but the package needs some real world usage on Windows though. Please report any issues you might find to the Github issues page. Any feedback is welcome! 😊

Running the tests

git clone
cd Flask-Resize
pip install tox

You can also run the tests inside docker:

docker-compose --build up

Or to run a single python version’s tests:

docker-compose run py36

Note that the tests in docker are run with all dependencies installed. See docker-compose.yml for more info.

Generating the docs

git clone
cd Flask-Resize
pip install -r requirements_docs.txt
python docs clean build serve

Now you should be able to view the docs @ localhost:8000.


Fork the code on the Github project page then:

git clone
cd Flask-Resize
pip install '.[full,test,test_s3]' -r requirements_docs.txt
git checkout -b my-fix
# Create your fix and add any tests if deemed necessary.
# Run the test suite to make sure everything works smooth.
git commit -am 'My fix!'
git push

Now you should see a box on the project page with which you can create a pull request.