Explore the System One model
Jev Playground
Paste your state, ask a typed question, get a decision with probabilities.
Load an example for a demo preview, or enter your own state and question.
/ INTRODUCTION
What Is the Jev Playground?
Jev is TypeSafe AI’s System One model. It evaluates the state you provide against questions with defined answer shapes. Instead of writing prose, it returns typed decisions and probabilities your code can use. VerdictKit lets you build a request without signing in and inspect clearly marked demo JSON; live evaluations require a configured server API key.
/ THE PRIMITIVES
Choice, Score and Noul
Three question types cover three different decision shapes. Pick the type before you write the question.
Choice
Pick exactly one option from your named set. Read the selected label, full probability distribution and confidence.
Score
Rate a state against ordered descriptions. Get a weighted score, legend, probabilities and confidence.
Noul
Ask a yes/no question and get one number: the probability that the answer is yes. Explore noul questions.
/ EXAMPLE RUNS
From state to decision.
These are preset examples. Their probabilities are not real Jev predictions. A genuine API result is labeled LIVE RUN in the tool.
Route a support ticket
“My card was charged twice.” → Choice among billing, technical and sales.
billing0.88Detect urgency
“Checkout is down. Please help ASAP.” → Noul yes/no probability.
yes0.95Rate frustration
“I have asked three times.” → Score across calm, frustrated and angry.
score1.05Demo probabilities are preset illustrations, not live model output. More Jev AI examples.
/ FOR DEVELOPERS
JSON Output
Every answer has a predictable shape. See the complete Jev JSON output schema, field reference and parsing pitfalls.
Explore Jev JSON output/ FOR DEVELOPERS
Use the Jev API
Start with the official endpoint, key setup, request examples, error codes and current pricing.
Read the Jev API guideCompare model costs and VerdictKit plans on the Jev pricing page.
/ FAQ
Questions about Jev
How much does it cost?
Demo previews are free. A configured playground offers two guest live runs per UTC day without signup; a Google account receives ten per UTC day. Run Pack, Pro and Batch are planned and not yet for sale.
Do I need an account to try it?
No account is needed for demo previews or the two-run daily guest trial. Sign in with Google for ten live runs per day on the Free account. Both allowances reset at 00:00 UTC when live access is configured.
Is this the official TypeSafe playground?
No. This site is operated by VerdictKit and is not affiliated with TypeSafe AI.
What is Jev?
Jev is TypeSafe AI’s System One model for typed decisions against a supplied state.
What’s the difference between choice, score and noul?
Choice selects an option, Score rates ordered levels, and Noul returns a yes/no probability.
Why does Jev return probabilities instead of a plain answer?
Probabilities let your code set thresholds and route uncertain cases for review.
How fast is Jev?
It is designed for fast decisions. Actual latency depends on state size, API load and network; benchmark your own use case.
What does the Jev API cost?
TypeSafe currently lists $0.042 per million input tokens for Jev 1.13, with free output tokens. Verify current pricing.
Can I use playground output in production?
Demo probabilities are prefilled illustrations and are not real predictions. Validate live output and thresholds before production use.
Where can I learn more about the Jev API?
Read our API guide and the official TypeSafe documentation.