What is py4web?

PY4WEB is a web framework for rapid development of efficient database driven web applications. It is an evolution of the popular web2py framework, but much faster and slicker. Its internal design has been much simplified compared to web2py.

PY4WEB can be seen as a competitor of other frameworks like Django or Flask, and it can indeed serve the same purpose. Yet PY4WEB aims to provide a larger feature set out of the box and to reduce the development time of new apps.

From a historical perspective, our story starts in 2007 when web2py was first released. web2py was designed to provide an all-inclusive solution for web development: one zip file containing the Python interpreter, the framework, a web based IDE, and a collection of battle-tested packages that work well together. In many ways web2py has been immensely successful. Web2py succeeded in providing a low barrier of entry for new developers, a very secure development platform, and remains backwards compatible until today.

Web2py always suffered from one problem: its monolithic design. The most experienced Python developers did not understand how to use its components outside of the framework and how to use third party components within the framework. We thought of web2py as a perfect tool that did not have to be broken into pieces because that would compromise its security. It turned out that we were wrong, and playing well with others is important. Hence, since 2015 we worked on three fronts:

  • We ported web2py to Python 3.

  • We broke web2py into modules that can be used independently.

  • We reassembled some of those modules into a new more modular framework … PY4WEB.

PY4WEB is more than a repackaging. It is a complete redesign. It uses some of the web2py modules, but not all of them. In some cases, it uses other and better modules. Some functionality was removed and some was added. We tried to preserve most of the syntax and features that experienced web2py users loved.

Here is a more explicit list (see From web2py to py4web for more details if you come from web2py):

  • PY4WEB, unlike web2py, requires Python 3.

  • PY4WEB, unlike web2py, can be installed using pip, and its dependencies are managed using requirements.txt.

  • PY4WEB apps are regular Python modules. This is very different from web2py. In particular, we ditched the custom importer, and we rely now exclusively on the regular Python import mechanism.

  • PY4WEB, like web2py, can serve multiple applications concurrently, as long as the apps are submodules of the apps module.

  • PY4WEB, unlike web2py, is based on ombott (a reduced and faster spin-off of Bottle) and in particular uses a Bottle-compatible request object and routing mechanism.

  • PY4WEB, unlike web2py, does not create a new environment at every request. It introduces the concept of fixtures to explicitly declare which objects need to be (re)initialized when a new http request arrives or needs cleanup when completed. This makes it much faster than web2py.

  • PY4WEB, has a new session object which, like web2py’s, provides strong security and encryption of the session data, but sessions are no longer stored in the file system - which created performance issues. It provides sessions in cookies, in redis, in memcache, or optionally in database. We also limited session data to objects that are json serializable.

  • PY4WEB, like web2py, has a built-in ticketing system but, unlike web2py, this system is global and not per app. Tickets are no longer stored in the filesystem with the individual apps. They are stored in a single database.

  • PY4WEB, like web2py, is based on pydal but leverages some new features of pydal (RESTAPI).

  • PY4WEB, like web2py, uses the yatl template language but defaults to square brackets delimiters to avoid conflicts with model JS frameworks, such as Vue.js and angular.js. Yatl includes a subset of the web2py helpers.

  • PY4WEB, unlike web2py, uses the pluralization library for internationalization. In practice, this exposes an object T very similar to web2py’s T but it provides better caching and more flexible pluralization capabilities.

  • PY4WEB comes with a Dashboard APP that replaces web2py’s admin. This is a web IDE for uploading/managing/editing apps.

  • PY4WEB’s Dashboard includes a web based database interface. This replaces the appadmin functionality of web2py.

  • PY4WEB comes with Form and Grid objects that are similar to web2py’s SQLFORM and SQLFORM.grid.

  • PY4WEB comes with an Auth object that replaces the web2py one. It is more modular and easier to extend. Out of the box, it provides the basic functionality of register, login, logout, change password, request change password, edit profile as well as integration with PAM, SAML2, LDAP, OAUTH2 (google, facebook, and twitter).

  • PY4WEB leverages PyDAL’s new tags functionality to tag users with groups, search users by groups, and apply permissions based on membership.

  • PY4WEB comes with with some custom Vue.js components designed to interact with the PyDAL RESTAPI, and with PY4WEB in general. These APIs are designed to allow the server to set policies about which operations a client is allowed to perform, but give the client flexibility within those constraints. The two main components are mtable (which provides a web based interface to the database similar to web2py’s grid) and auth (a customizable interface to the Auth API).

The goal of PY4WEB is and remains the same as web2py’s: to make web development easy and accessible, while producing applications that are fast and secure.


Many thanks to everyone who has contributed to the project, and especially:

Special thanks to Sam de Alfaro, who designed the official logo of py4web. We friendly call the logo “Axel the axolotl”: it magically represents the sense of kindness and inclusion. We believe it’s the cornerstone of our growing community.