Meet Jev.
The AI that decides,
not writes.
Understand the AI model that doesn't write text — it makes fast, typed, confident decisions your software can act on. This is your end-to-end, 101-level guide — the history, the founder, how it works, and a live sandbox to play with.
4 lessons · ~25 min · interactive
“Stripe payouts have been failing for 3 days and I’m losing sales. Please help ASAP.”
The curriculum
Four lessons, end to end
Work through them in order, or jump straight to what your session needs.
What is Jev?
Meet the first 'System One Model' — an AI that returns typed decisions with probabilities instead of generating text.
History & Founder
Where Jev came from: TypeSafe AI, founder Diogo Almeida, and why it's named after an economist.
How it works
System One vs System Two, the three question types (Noul, Choice, Score), and the RLCD training method.
Use cases
Ticket triage, agent guardrails, model routing, refund review and more — where Jev shines in production.
“If the answer can be picked from a finite set of options, use Jev. If the answer has to be thought up, use an LLM.”
The single sentence to remember for your session