APB is a simple, yet powerfull, project build system that inherits some ideas from Ant and Maven while trying to avoid the use of complex XML files to define the metadata of the project.

APIviz is a JavaDoc doclet which extends the Java standard doclet. It generates comprehensive UML-like class and package diagrams for quick understanding of the overall API structure.

Apodora is an automated functional testing framework for web applications. It is used to create automated functional tests for web applications.

Apodora Features:
* Increased Test Coverage
* Decreased Test Management
* Robust Automation Object Repository
* Automate Testing of Multiple Technologies
* Enhanced Extensibility
* Accessible Functionality
* Advanced and Beginner Features
* Based in IronPython

A framework to optimize ABC, SWC and SWF files. Apparat features include:
* Compression
* Code analysis
- UML diagram generation
- Bytecode flowgraph generation
- Static check for [Abstract] methods
- Detailed ABC information
- Code coverage instrumentation
- Typesafe trace() removal keeping side-effects
- ASMify existing code
* Optimization

Appcelerator is a next-generation, open source web platform. The Appcelerator Platform incorporates the best of RIA and SOA-based technologies and design principles into one fully-integrated solution

Appium is an open source test automation tool for use with native and hybrid mobile apps. It drives iOS and Android apps using the WebDriver JSON wire protocol. Appium aims to automate any mobile app from any language and any test framework, with full access to back-end APIs and DBs from test code.

applitude is a runtime framework and a domain-specific language for iPhone application development. It is an extended, iPhone-only version of the Applause project.

Unit testing asserts can be difficult to use. Approval tests simplify this by taking a snapshot of the results, and confirming that they have not changed.

AppScale is a platform that allows users to deploy and host their own Google App Engine applications. It executes automatically over Amazon EC2, Google Compute Engine, Rackspace, Eucalyptus, CloudStack, OpenStack, as well as Xen, VirtualBox, VMWare, and KVM. It has been developed and is maintained by AppScale Systems, Inc., in Santa Barbara, CA. It supports the Python, Java, PHP, and Go Google App Engine platforms.

Appsta is designed to make bootstrapping new Rails applications much easier. It provides a helper library for writing Rails templates, to quickly setup your projects on Heroku, GitHub, and other things to get your app up and running quickly.