current follows the provider, with the epoch of model behaviour recorded on every answer and its quality re-checked against the conformance suite every day and after every change we detect. Only active versions can be pinned by a new judgment, and GET /engines lists those. If an exact version your judgments have used is retired, your organization’s owners and admins get an email. Judging costs the same on every engine: you pay per judgment, by size class.
Laya, a small engine we host ourselves for short text, is coming. It gets a page here once its first version passes the conformance suite; until then, use Jev current.