Oracle Application Express abbreviated APEX, previously named Oracle HTML DB is a web-based software development environment that runs on an Oracle database. It is fully supported and comes standard at no additional cost with all Oracle Database editions and, starting with Oracle 11g, is installed by default as part of the core database install.
APEX can be used to build complex web applications which can be used in most modern web browsers. The APEX development environment is also browser-based.
Oracle Application Express can be installed on any Oracle database from version 9.2 or higher, and starting from Oracle 11g it is installed with the database by default. APEX 4.0 and higher can be installed on an Oracle 10.2.0.3 or higher database. APEX 5.0 and higher can be installed on all editions SE1, SE, and EE of the Oracle database, 18.104.22.168 or higher with a valid Oracle Database Technical Support agreement; it can also be used with Oracle Database 11g Express Edition XE, but is supported through the Oracle Technology Network discussion forum, and not through Oracle Support Services.
Application Express has gone through many name changes since its inception in 2000. Names include:
APEX was created by Mike Hichwa, a developer at Oracle, after development of his previous project, Web DB, started to diverge from his original vision. Although APEX shares some functionality with Web DB, it was developed from scratch and there's no upgrade path from Web DB to APEX. When tasked with building an internal web calendar, Hichwa enlisted the help of Joel Kallman and started development on a project called Flows. Hichwa and Kallman co-developed the Web Calendar and Flows, adding features to Flows as they needed them to develop the calendar. Early builds of Flow had no front-end so all changes to an application had to be made in SQL*Plus via inserts, updates and deletes.
APEX is used internally by Oracle to develop some of its support sites. The AskTom knowledgebase and online store both run on APEX. The Metalink support site ran on APEX for some time before it was eventually replaced by an Oracle ADF solution.