FAQ
Is Jev open source?
Section titled “Is Jev open source?”No. What’s open is the API, the official SDKs (MIT), and the docs. SemIf, kev, and NanoJev are community projects replicating the interface idea on open models — not Jev’s weights (see Ecosystem).
How much free credit do I get?
Section titled “How much free credit do I get?”Media reports (36kr and others, 2026-09) say $5 on sign-up (~120M input tokens). Not verified by this site — whatever console.typesafe.ai shows after you register is the truth. Confirmed pricing: input $0.042 per million tokens, output free (official).
How much can I send at once?
Section titled “How much can I send at once?”≤ 64k tokens per request, with state + the longest single question ≤ 32k tokens (official). Longer content: chunk or retrieve first, then ask about relevant fragments (see RAG passage filtering).
Does it replace an LLM?
Section titled “Does it replace an LLM?”No — it isn’t trying to. Jev only answers within the three question types (Capabilities) and generates no text. The common architecture is Jev in front, LLM behind: Jev routes/filters/approves, and the LLM handles only what truly needs it (Model routing).
Is “can never hallucinate” true?
Section titled “Is “can never hallucinate” true?”It’s an over-simplification of a type-safety claim. The official meaning: answers are constrained to the question’s type, so there is no out-of-format fabricated text. Wrong options and mis-scores are still possible — hence confidence gating (see Limitations).
Can it run locally?
Section titled “Can it run locally?”Not officially. Community replicas run offline on consumer GPUs for learning, but never extrapolate their behavior to Jev itself.
What are the rate limits?
Section titled “What are the rate limits?”250k tokens/s + 1200 requests/min; exceed them and you get 429. Officially noted as subject to change (API reference has the full error and backoff guidance).
Which official SDKs exist?
Section titled “Which official SDKs exist?”Python (pip install typesafe-sdk, ≥3.10) and TypeScript/JavaScript (npm i @typesafe-ai/sdk), both MIT, both with typed answers and retry policies (Python guide / JavaScript guide).
Vercel switched and got much faster — real?
Section titled “Vercel switched and got much faster — real?”Vercel offering Jev on AI Gateway is real (official announcement). The “5–18× faster” figures are vendor-reported and media-relayed; this site has not verified them (see the disputes table in Limitations).
Why the names Jev / System One?
Section titled “Why the names Jev / System One?”Per the launch blog: Jev from the Jevons paradox (cheap decisions → more decisions), System One from Kahneman’s fast-thinking system (see What is Jev).
Anything else?
Section titled “Anything else?”- Start here: Get started
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