Made with Jev

Everything here is made with Jev — the same typed, calibrated decision that returns one key, a probability for every option, and a confidence score in a single round trip. Open any of them, then build your own.

Jev is TypeSafe AI's first System One model, launched in September 2026 by Diogo Almeida — the OpenAI researcher who co-invented RLHF and InstructGPT, the methods behind ChatGPT. Instead of writing prose, Jev emits typed structured values directly: one of the classes you defined, calibrated probabilities across all of them, and a confidence value. The demos below all run through the same hosted endpoint you get with a key, so what you see is exactly what you can ship.

One call carries your state and a map of typed questions; Jev answers them all in a single parallel pass.

Why 'made with Jev' looks different

Jev does not generate text token by token. A single non-autoregressive pass produces every answer at once, so there is nothing to parse, nothing to repair, and — because the output is locked to the type you declared — nothing to hallucinate. That is what lets a tool built on Jev return a decision in roughly 70–500ms, about 40–200x faster than prompting a frontier LLM.

Tools made with Jev

PR JudgeJev as a judgeScores a pull request with a typed verdict + confidenceOpen →Model RouterRoutingPicks the right downstream model in one typed callOpen →Prompt Injection DetectorGuardrailFlags injection attempts before they reach your modelOpen →Semantic GrepClassificationFilters lines by meaning, not regexOpen →Fraud Email DetectorClassificationTyped fraud / safe call with calibrated probabilityOpen →Ask 100 PersonasBatchFan one question across a crowd of typed votersOpen →

Games made with Jev

The games are the same primitive turned into an opponent or a referee: every move is a typed Jev decision, so you can watch a calibrated model reason under real constraints.

Jev 2048GameJev plays 2048 by choosing a direction each turnPlay →Jev TetrisGameA typed decision drives every dropPlay →CalibrationGameBet against Jev's confidence and see if it holdsPlay →WikiracerGameJev navigates Wikipedia by picking the next linkPlay →

Make something with Jev

Grab a jv_live_ key and hit POST https://jevtypesafeai.com/api/v1/decide (or the official POST https://api.typesafe.ai/v1/systemone). Define your options, send the state you want a decision on, and you get back a typed answer you can act on immediately. That is all any tool or game on this page does.

FAQ

What does 'made with Jev' mean?

Every tool and game here calls the Jev decide endpoint for its decisions — the same typed, calibrated API you get with a key. There is no separate SDK magic; each one sends state plus typed questions and acts on the typed answer.

Can I build the same things?

Yes. Try any demo free in the browser, then generate a jv_live_ key and point your own code at the same endpoint. The request shape is identical to what powers these pages.

Why are they so fast?

Jev answers in a single non-autoregressive pass rather than generating text token by token, so a decision returns in roughly 70–500ms — about 40–200x faster than prompting a frontier LLM.

See also: All tools · All games · What is Jev · Pricing

Make something with Jev

Try it free in the browser, then grab a jv_live_ key and ship your own.

▶ Try Jev free Get an API key →