Ruby on Rails!

PHP (version 4 or 5) framework with a thin model layer. Includes an ActiveRecord class for database agnostic (mostly) data retrieval. Good community support in its forums.

Symfony is a set of reusable PHP components and a PHP framework for web projects.

Extending the art & spirit of PHP, Zend Framework is based on simplicity, object-oriented best practices, corporate friendly licensing, and a rigorously tested agile codebase. Zend Framework is focused on building more secure, reliable, and modern Web 2.0 applications & web services, and consuming widely available APIs from leading vendors like Google, Amazon, Yahoo!, Flickr, as well as API providers and cataloguers like StrikeIron and ProgrammableWeb.

Yii is a high-performance component-based PHP framework best for Web 2.0 development.Yii comes with rich features: MVC, DAO/ActiveRecord, I18N/L10N, caching, authentication and role-based access control, scaffolding, testing, etc. It can reduce your development time significantly.

Grails is a high-productivity web framework based on the Groovy language that embraces the coding by convention paradigm, but is designed specifically for the Java platform.

Agile Toolkit is a PHP framework for developing Web User Interfaces. Inspired by desktop GUI it provides a full object-oriented foundation for Business and Presentation logic of your web software. Agile Toolkit is notable for it's simple of use and development efficiency.

Wakanda is an open source full-stack JavaScript platform to develop and deploy mobile & Web apps in the enterprise. With Wakanda, you can visually create your data model, associated CRUD operations to user groups, and your data is right away available through an automatically generated REST API. You can use Wakanda’s JavaScript client side connectors to consume the API without effort whether you are using Angular, React, Aurelia or another framework.

Web2py is an open source web application framework. Web2py is written in the Python language and is programmable in Python. Since web2py was originally designed as a teaching tool with emphasis on ease of use and deployment, it does not have any project-level configuration files

Play is a web application framework, written in Scala and Java, which follows the model–view–controller (MVC) architectural pattern.

Portofino is a free and open source web framework that helps developers create outstanding enterprise applications by addressing three specific needs: productivity, features and architecture.

Sinatra is a free and open source software web application library and domain-specific language written in Ruby. It is an alternative to other Ruby web application frameworks such as Ruby on Rails, Merb, Nitro, Camping, and Rango. It is dependent on the Rack web server interface.