Jev, explained without the hype
Jev is TypeSafe’s first public System One model. It does not write text. You hand it some state and a set of typed questions, and it hands back probabilities. These pages cover what that means, how to call it, what it costs, and what it is not.
- 01 What Jev is, in plain terms
A judgment model, not a chat model. You give it some text and a set of typed questions; it gives back probabilities. It cannot write you a sentence, and that is the point.
- 02 What people are actually building with Jev
Demonstrations you can watch, open-source projects you can read, and a catalogue of every deployment reported in public in the model's first days — agents, support queues, ranking, games and robots, and a consumer slice that is almost empty.
- 03 How to use Jev
Three ways to reach the same model — Vercel AI Gateway, TypeSafe's own API, and OpenRouter — with the working code for each, and the one naming difference that silently breaks a port between them.
- 04 What Jev costs
Input tokens are billed, output tokens are free. Work out what your own workload costs before you build on it.
- 05 Jev compared with chat models
They are not competitors so much as different shapes. A chat model writes; a judgment model decides. Here is where each one fits.
- 06 Jev and openjev are not the same thing
openjev is a community effort to reproduce the idea on hardware you own. It is not a client for Jev, and it is not built by TypeSafe.