[3] It is the de facto standard for providing accessibility to free and open desktops, like Linux or OpenBSD, led by the GNOME Project.

In the case of GNOME, there are two different APIs, one for the client-side (AT-SPI) and a different one for the server-side (Accessibility Toolkit (ATK)) due to historical reasons related to the underlying technologies.

[4] AT-SPI was originally designed for using Common Object Request Broker Architecture, an object-based IPC/RPC technology, for its transport protocol.

The GNOME widget system, GTK+, or Mozilla applications like Firefox and Thunderbird for Linux implement ATK, so they communicate out-of-box with AT-SPI.

The main development force behind ATK was the Accessibility Program Office (APO) of Sun Microsystems, Inc. (now Oracle) with contributions from many community members.