The WebSub protocol

WebSub (formerly PubSubHubbub) is a standard protocol to instantly receive (push) notifications when some new content is available on a remote server, for instance when a new article is available via RSS / ATOM.

FreshRSS supports WebSub natively. Just like for the FreshRSS API to work from a mobile phone, supporting WebSub requires that your FreshRSS instance is routable (that is to say, with a public IP, that can be accessed from third-party servers).

WebSub terminology

There are tree main concepts:

publisher: Web site publishing content such as RSS / ATOM feeds;
subscriber: Feed aggregator such as FreshRSS;
hub: Intermediate technical component in charge of notifying all subscribers instantly when a publisher has some new content. The same hub can serve several publishers and their subscribers. Some publishers have a built-in hub.

Enabling WebSub in FreshRSS

FreshRSS supports WebSub natively, but requires a public address (read from the base_url configuration), and requires the ./FreshRSS/p/api/ folder to be publicly accessible (just like for other FreshRSS APIs).

During the initial Web-based setup, support for WebSub is enabled if the server hosting FreshRSS appears to have a public address. In any case, check your ./data/config.php for:

'base_url' => 'https://freshrss.example.net/',
'pubsubhubbub_enabled' => true,

Additional logs about WebSub are available in ./FreshRSS/data/users/_/log_pshb.txt

Test WebSub compatibility of your FreshRSS instance

You can test that WebSub works properly in your FreshRSS instance with a service such as:

http://push-tester.cweiske.de

When you create a new article, it should instantly be available in your FreshRSS instance.

Examples of feeds using WebSub

Many individual feeds and platforms already offer instant notifications through WebSub, such as: Friendica instances, WordPress (from WordPress.com or with an extension), Blogger sites, Medium sites, etc.