Activity Streams/Primer/Application type

The definition of the Application type in the Activity Vocabulary is Describes a software application.

This can cover all types of software applications. However, in the context of social network software, this is primarily for a Web or mobile client application.

For example, an iOS application that shows the user their own home timeline would be an Application.

Another example would be a bot that posts quotes from Emily Dickinson. In this case, the Application would also be an ActivityPub "actor", with an inbox, outbox, and other actor properties.

Sometimes a software service can act like an application. For example, a search index bot would likely be an Application.

The generator property of an Object may be a Application. Similarly, the instrument property of an Activity may be an Application.

FEP D8C2 recommends using the Application object type to identify OAuth 2.0 clients.

Guidance for publishers

• Use Application types where an actor type can be used.
• Use Application for generator.

Guidance for consumers

• Treat Application as a client software application, unless otherwise defined.
• Many implementations use the Application type to represent an account server, even though this is better represented by Service.