The algolia plugin is an official plugin, so is it possible to use it on the hosted discourse service? If not, are there other alternatives such as open-source crawlers that people use successfully to get data from a hosted discourse into algolia?
It is, on the Enterprise tier. The easy way to determine is to visit https://www.discourse.org/plugins, and if an official plugin is not otherwise on that list, it’s Enterprise.
Are you only interested in populating Algolia? The plugin does that and additionally incorporates the Algolia results in the Discourse search interface. There may be some clever ways to populate the index…
It isn’t for small sites (you can always check pricing and features of each plan at Discourse pricing | Discourse - Civilized Discussion). If the Algolia plugin is needed for your small site, our hosted plans won’t work for your community.
However, small communities can use self-hosted Discourse, where you’d also be able to use the Algolia plugin.