Jev
Jev is TypeSafe AI's first System One model, launched in early access on September 15, 2026. It is not a chatbot: you send unstructured or structured state plus typed questions and get structured answers your code can branch on.
Provider
TypeSafe AI
Model family
TypeSafe System One
System One decision model
Cost tier
Jev
Status
Current
Release Sep 15, 2026
Why teams choose it
Official spelling is Jev (William Stanley Jevons), not Jeva
The API model field in the quickstart is jev-latest.
TypeSafe's launch post prices input at $0.042 per million tokens ($42 per billion) and calls output too cheap to meter
Homepage workflow copy cites 193.6× faster and 444.6× cheaper versus LLM wrappers on TypeSafe's own System One workflows, using GPT-6 Astra and Claude Fable 5.1 as the reference average.
Schema matching is guaranteed: the model cannot emit an undeclared Choice option
That is not a claim that the selected option is factually correct. Access is a waitlist / early-access API key.
Tradeoffs to know
- Jev does not generate chat, code, or free-form text. JSON-mode GPT/Claude is a different job.
- Early access. TypeSafe's speed/cost headlines are vendor workflow evals, not a public gold-set bake-off.
- Choice cardinality is documented at 255 options. The Doom demo uses structured game state, not pixels.
When not to use this
- Not ideal for simple tasks where cheaper models in the same lineup are good enough.
- Avoid for latency-sensitive real-time chat when raw response speed outweighs reasoning depth.
- Confirm limits, pricing, and regional availability on the provider side before committing production workloads.
Technical specs
- Inputs
- text
- Outputs
- structured
- Capabilities
- typed decisions, choice classification, scoring, noul yes-no probability, calibrated confidence, parallel questions, workflow routing
- License
- Proprietary API (early access)
- Model string
jev
Benchmarks
{
"api_id": "jev-latest",
"source": "https://typesafe.ai/blog/introducing-system-one-models-and-jev",
"endpoint": "https://api.typesafe.ai/v1/systemone",
"vendor_reported": true,
"latency_ms_range": [
70,
500
],
"choice_max_options": 255,
"input_usd_per_million_tokens": 0.042,
"output_usd_per_million_tokens": 0
}Jev FAQ
What is Jev?
Jev is TypeSafe AI's first System One model, launched in early access on September 15, 2026. It is not a chatbot: you send unstructured or structured state plus typed questions and get structured answers your code can branch on. The documented model alias is jev-latest on POST https://api.typesafe.ai/v1/systemone. Que...
When does Jev fit best?
Classify, route, and score tickets or documents inside ordinary software
What should teams watch out for with Jev?
Jev does not generate chat, code, or free-form text. JSON-mode GPT/Claude is a different job.
Explore next
Models, tools, and comparisons that connect to this reference.