WTForms is awesome for validating POST data. What about other request data?
The Flask-Inputs extension adds support for WTForms to validate request data from args to headers to json.
To install Flask-Inputs, simply:
$ pip install flask-inputs
JSON validation requires jsonschema:
$ pip install jsonschema
Documentation is available at http://pythonhosted.org/Flask-Inputs
Fork the repository, make changes and add a test which shows that the bug was fixed or that the feature works as expected with 100% coverage. Send a pull request.