Pusher Glossary

The Pusher Glossary is a curated resource which defines brand and industry-specific terms you'll find in our documentation. Think something's missing? Reach out to the team


Access token

Access tokens are used in token-based authentication to allow access to a certain resource (for example, file, database, or most commonly, API). These tokens contain security credentials needed for login and it identifies the user. You need access tokens when building an authentication or implementing authentication with a third-party platform.

Access tokens can be in any string format. However, you will often see them in the JSON Web Token (JWT) format when making calls to a specific API. Tokens are sent to the server to access some sort of API or data.

With Pusher, we use access tokens to authorize subscriptions to private and presence channels.

Anonymous access

Anonymous access allows end users to access public services, apps, or content without end users needing to submit their credentials.

In Pusher, for apps which don’t require authorization, developers can leave out the authorization header in the request.

In the case of an application allowing anonymous, but authenticated access, the backend can pass the client an access token without a user identifier. The service will treat the client as acting on behalf of an anonymous user.


Apple Push Notification service (APNs), developed by Apple Inc. is a remote notification service used to send notifications and data to devices using OS X and iOS. It’s used to send third-party notifications over a secure (encrypted) connection.

With Pusher Beams, we rely on APNs to deliver push notifications to iOS application users on your behalf. Read more about how to Configure APNs when using Pusher Beams.

App Cluster

The app_cluster represents the physical region of the servers that handle requests from your Channels app.

A cluster represents the physical location of the servers that handle requests from your Channels app. When you create a Channels app, you can choose which cluster it exists in.

Here’s everything you need to know about Pusher Channel clusters.

App ID

The app_id is an app identifier, which is a string with a limited character set.

App Key

The app_key is an opaque identifier used on the client side to indicate the app.

Read more on how to manage Pusher Channel keys in mobile apps.

App Secret

The app_secret is used by the application server to sign requests going to Pusher (either via the API or auth flow). Pusher then verifies the authenticity of the request by verifying the signature.

Authenticated user

When using Pusher Channels, user authentication means the system identifies who the user is. Pusher client libraries can make calls to endpoints of your choice so your end users can be authenticated.

Read more about user authentication.

Authorized connections

Authorized connection is a feature in Pusher Channels. It enables you to authorize every single connection to your Channels app.

Learn more about Pusher authorized connections.

Authorized user

When using Pusher Channels, user authorization means the system determines what permissions a user has, i.e what channels they are authorized to subscribe to.