Apache OpenOffice，又称OpenOffice、AOO，原称为OpenOffice.org，是一套开放源代码的办公室软件，可以在多种操作系统上运作。缺省的文档交换格式是已经成为ISO标准的开放文档格式（ODF，OpenDocument Format），此外也支持Microsoft Office 97至2016的文档格式，以及其余常见的文档文件。在转交Apache软件基金会前，软件通常称为「OpenOffice」或简称「OOo」，但因为商标的争议，正规的叫法是「OpenOffice.org」。

OpenOffice.org (OOo), commonly known as OpenOffice, is a discontinued open-source office suite, while descendant projects are still being developed. It was an open-sourced version of the earlier StarOffice, which Sun Microsystems acquired in 1999, for internal use. Sun open-sourced the software in July 2000 as a competitor to Microsoft Office, releasing version 1.0 on 1 May 2002. In 2011 Oracle Corporation, the then-owner of Sun, announced that it would no longer offer a commercial version of the suite and soon after donated the project to the Apache Foundation. Apache renamed the software Apache OpenOffice. Other active successor projects include LibreOffice (the most actively developed) and NeoOffice (commercial, only for OS X).