Oracle Application Express (Apex) is a rapid web application development tool for the Oracle database. Application Express can be used to build web-based applications from a standard web browser (web-based development environment).
APEX is built on top of mod_plsql. The initial development was known as "Project Marvel" and "WebDB".
Oracle Portal was developed from the WebDB code base and later also HTMLDB (a lighter database-on-the-web version of Portal).
Apex 3.1 was released in February 2008 with interesting features like Interactive Reporting, Runtime-Only Installation, etc.
APEX can be installed within an Oracle 9i R2 or higher database (from the Supplemental CD). Starting from Oracle 11g APEX will be pre-installed with the database. The latest version can be downloaded from OTN.
APEX can be used free of charge on any validly licensed Oracle database.
 Reference sites/ apps
Some of the most well known applications developed with APEX are:
- AskTom (developed by Tom Kyte)
- Oracle's Metalink support site had been running on APEX, but was replaced with a Flash version in September 2008 and put back to a HTML version in June 2012.
- Oracle's online store
 Also see
- APEX FAQ - APEX Frequently asked questions