The Jev playground

The Jev playground is the fastest way to feel what the model does: type a decision, hit run, and get back one typed answer with a probability for every option and a confidence score — in milliseconds, right in your browser.

TypeSafe AI's own access is waitlisted, so most people cannot just try Jev. The playground on this site runs your calls against a live key, so there is no waitlist and nothing to install — you interact with the real System One model, not a mock.

What you can try

• choice: pick one label from your options with calibrated probabilities
• gate: get a yes/no on whether an action should proceed
• score and check: rank options or verify a condition
• See the latency (~70–500ms) and the confidence value on every response

From playground to code

Once a decision behaves the way you want in the Jev playground, the same request works from code unchanged: POST https://jevtypesafeai.com/api/v1/decide with a jv_live_ key, or the official POST https://api.typesafe.ai/v1/systemone. The playground shows you the exact shape of the state and questions you send, so moving to production is copy-paste.

Why start here

Reading about calibration and typed output is one thing; watching a Jev decision come back constrained to your enumeration, with confidence that actually tracks correctness, makes it obvious. Open the playground, run a few decisions, and if it fits grab a key with no waitlist.

See also: Open the playground · Get access to Jev · What is Jev

Related: Jev API key · Jev classifier · Jev AI agent