The Jev API

The Jev API is a single HTTP endpoint that turns a state plus typed questions into calibrated decisions — a choice, a score, or a yes/no probability — in one round trip. No prose to parse, no schema to validate. This is the whole surface on one page: endpoint, auth, a working call, the response, pricing and limits.

Unlike a chat API, the Jev API doesn't generate text — it decides. You send the context (state) and the exact questions you want answered, each with a type, and you get back a typed value with a calibrated probability behind it. Because the shape is fixed by your request, the API physically cannot return a malformed response or an invalid type, so your code branches on the answer directly.

The endpoint & auth

There are two hosts, same request shape. The instant, self-serve route is our hosted gateway; the official route is TypeSafe's own API. Both authenticate with a Bearer key.

# Hosted (instant jv_live_ key from this site):
POST https://jevtypesafeai.com/api/v1/decide
Authorization: Bearer jv_live_...

# Official TypeSafe:
POST https://api.typesafe.ai/v1/systemone
Authorization: Bearer <your key>

Your first API call

One request, three typed answers — a route to branch on, an urgency score, and a calibrated escalation flag:

curl https://jevtypesafeai.com/api/v1/decide \
  -H "Authorization: Bearer $JEV_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "state": "Customer: I was charged twice and nobody has replied for 3 days.",
    "questions": {
      "route":    { "type": "choice", "instructions": "Where should this go?",
                    "criteria": { "billing": "money", "bug": "broken", "account": "login" } },
      "urgency":  { "type": "score",  "instructions": "How urgent is this?",
                    "criteria": ["routine", "today", "urgent", "critical"] },
      "escalate": { "type": "noul",   "instructions": "Escalate to a human now?" }
    }
  }'

The three primitives

• choice — returns one of your labelled options (up to 255), with per-option probabilities. For routing, classification, intent.
• score — returns a position on an ordered scale you define, plus the distribution. For rating urgency, quality, risk.
• noul — a calibrated yes/no as a probability between 0 and 1. For gates, filters, guardrails.

Ask several at once in a single call — each comes back independently typed under answers, so one request can classify, score and gate the same input together.

From TypeScript

const res = await fetch("https://jevtypesafeai.com/api/v1/decide", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.JEV_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    state: "Customer: I was charged twice and nobody has replied for 3 days.",
    questions: {
      route:    { type: "choice", instructions: "Where should this go?",
                  criteria: { billing: "money", bug: "broken", account: "login" } },
      urgency:  { type: "score",  instructions: "How urgent is this?",
                  criteria: ["routine", "today", "urgent", "critical"] },
      escalate: { type: "noul",   instructions: "Escalate to a human now?" },
    },
  }),
});
const { answers } = await res.json();
if (answers.escalate.noul > 0.7) handoffToHuman();

From Python

import os, requests

r = requests.post(
    "https://jevtypesafeai.com/api/v1/decide",
    headers={"Authorization": f"Bearer {os.environ['JEV_API_KEY']}"},
    json={
        "state": "Customer: I was charged twice and nobody has replied for 3 days.",
        "questions": {
            "route":    {"type": "choice", "instructions": "Where should this go?",
                         "criteria": {"billing": "money", "bug": "broken", "account": "login"}},
            "urgency":  {"type": "score",  "instructions": "How urgent is this?",
                         "criteria": ["routine", "today", "urgent", "critical"]},
            "escalate": {"type": "noul",   "instructions": "Escalate to a human now?"},
        },
    },
    timeout=30,
)
ans = r.json()["answers"]
print(ans["route"]["choice"], ans["escalate"]["noul"])

The response

You get back the resolved model, an answers map, and token usage. Each answer is typed: answers.route.choice is one of your criteria keys, answers.urgency.score is a number on your scale, answers.escalate.noul is a probability. Because the types are fixed, you branch in plain code — if (answers.escalate.noul > 0.7) — with no parsing, no regex, and no risk of malformed output.

Pricing

The Jev API is billed on input tokens only — output is free. On the hosted route that's $0.42 per million input tokens, roughly $0.001 per decision, prepaid from a small balance. Asking several questions in one call shares the input cost, so batching is cheap. See the pricing page for packs.

Limits & best practices

• Rate limits: 250,000 tokens/second and 1,200 requests/minute.
• Context: up to ~64k tokens for state + all questions (32k for state + a single longest question).
• Pin the model version (e.g. jev-1.13.0) in production so calibrated thresholds don't drift; jev-latest can change.
• Batch questions into one call rather than many — they run in parallel and share the state cost.
• Use the calibrated confidence to auto-handle the easy cases and escalate only the uncertain ones.

SDK or raw HTTP

The Jev API is a single POST, so you can call it with plain fetch/requests and a Bearer key — no SDK required. If you want typed helpers that read your key from the environment, the TypeScript SDK (@typesafe-ai/sdk) wraps the same endpoint. Either way the contract is identical.

Get a key and go

You can run the Jev API free in the browser playground with no key to confirm it fits, then get an instant hosted jv_live_ key on the pricing page and make your first real call in minutes. For the full field reference, batch endpoints and ready-made workflows, see the docs.

FAQ

See also: API docs & reference · How to use the API · Get a Jev API key · TypeScript quickstart · Pricing · Playground

Related: Jev API key · Jev playground · Jev price