1. Data source
  2. Decision schema
  3. Model inference
  4. Structured result
2 Decision schema 3 typed questions
  • judgmentchoicepassblockreview
  • evidence_strengthscorenoneweakmoderatestrong
  • needs_humannoulprobability 0–1

3 Model inference typesafe/jev-1.13

Waiting for a run.

4 Structured result

Run the demo to see the JSON answers, the highlighted pick and the final action.

Call Jev yourselfSame data and schema, straight to Flatkey. Set FLATKEY_API_KEY and run.
curl -sS https://router.flatkey.ai/api/alpha/decisions \
  -H "Authorization: Bearer $FLATKEY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "typesafe/jev-1.13",
  "state": "Claim: \"Jev checked 3,157 claims against sources with 78.9% balanced accuracy at roughly 0.2s per verdict and about 14 cents total cost.\"\n\nSource A: Blog excerpt — \"We evaluated mute probability models on 3,157 claim–source pairs. Balanced accuracy: 78.9%. Median latency ~0.2s. Total spend across the run: $0.14.\"\n\nSource B: Same post — \"Judgments collapse when evidence is missing or wrong; calibrate thresholds and cascade pass/block/review.\"\n\nTask: judge grounding of the claim against these sources only.",
  "questions": {
    "judgment": {
      "type": "choice",
      "instructions": "Judge whether the claim is grounded in the provided source evidence. Ignore world knowledge outside the snippets.",
      "criteria": {
        "pass": "The sources support the claim with enough specific evidence; no material contradiction",
        "block": "The sources contradict the claim, or the claim asserts facts the sources do not support",
        "review": "Evidence is partial, ambiguous, or conflicting enough that a human should decide"
      }
    },
    "evidence_strength": {
      "type": "score",
      "instructions": "How strong is the source support (or contradiction) for this claim, ignoring the claim author'\''s confidence.",
      "criteria": [
        "none",
        "weak",
        "moderate",
        "strong"
      ]
    },
    "needs_human": {
      "type": "noul",
      "instructions": "A human should review this claim–source pair before the judgment is trusted in production."
    }
  }
}'

No Flatkey key yet? Get one for Jev 1.13 →

Run with real Jev

Sign in and connect a key

  1. Sign in with Google.
  2. Connect your Flatkey or OpenRouter key on the next screen. Get a Flatkey key for Jev 1.13.
  3. Come straight back here and press Run again.

This site is for researching, sharing and cataloguing Jev use cases. Your key is only there to make trying Jev convenient: it is stored encrypted, used only for runs you trigger, never used for anything else, and you can delete it anytime.

About this use case

Use Jev as a grounding / hallucination judge: incoming state, Jev decision, routed outcome

Who / when

Audience

  • teams building RAG answer gates and citation checkers
  • eval engineers replacing chatty LLM-as-judge with a typed scorer
  • builders who need cheap pass / block / review signals on claims at volume

Triggers

  • an LLM judge writes long reasoning and still hallucinates about grounding
  • you need a cheap pass / block / review call after every claim–source pair
  • judgments collapse when evidence is missing or wrong and you need calibrated thresholds
  • you want auto-accept only when evidence strength and confidence are both high

The workflow

  1. 01
    Claim + sourcesClaim text and supporting or contradicting snippetsInput
  2. 02
    Judgmentpass / block / reviewJev
  3. 03
    Evidence strengthnone / weak / moderate / strongJev
  4. 04
    Cascade gateAccept, block, or route to humanYour code

Question shape

{
  "judgment": {
    "type": "choice",
    "instructions": "Judge whether the claim is grounded in the provided source evidence. Ignore world knowledge outside the snippets.",
    "criteria": {
      "pass": "The sources support the claim with enough specific evidence; no material contradiction",
      "block": "The sources contradict the claim, or the claim asserts facts the sources do not support",
      "review": "Evidence is partial, ambiguous, or conflicting enough that a human should decide"
    }
  },
  "evidence_strength": {
    "type": "score",
    "instructions": "How strong is the source support (or contradiction) for this claim, ignoring the claim author's confidence.",
    "criteria": [
      "none",
      "weak",
      "moderate",
      "strong"
    ]
  },
  "needs_human": {
    "type": "noul",
    "instructions": "A human should review this claim–source pair before the judgment is trusted in production."
  }
}

Gate policy

≥ 0.90

Auto-accept only when judgment is pass and evidence_strength is moderate or strong.

0.65–0.90

Cascade to a human or stronger judge; treat as review even if the top choice is pass.

< 0.65

Block the claim or answer; require better sources or a rewrite (also when judgment is block).

Failure modes

Pre-launch checks before you trust auto-routing:

  • Claims judged without any source snippets (judgments collapse when evidence is missing);
  • Wrong or swapped sources that look plausible but do not actually support the claim;
  • Prompt injection inside retrieved documents that tries to force a pass;
  • Using a chat model to rewrite long free-form justification after a typed judgment;
Keep exact work in code: evidence packaging, pass/block/review thresholds, cascade order and what gets published should be deterministic. Use Jev for the semantic grounding call; code enforces the gate bands.

FAQ

Why use Jev instead of another LLM as a grounding judge?

Chatty LLM-as-judge setups often write long reasoning and still drift. Mute models that only answer in probabilities were tested on thousands of claim–source pairs with ~78.9% accuracy, ~0.2s verdicts and cents-level cost. A typed Choice / Score / Noul layer behaves more like a measurement instrument than another chatbot.

How should I cascade pass / block / review?

Auto-accept only on pass with high confidence and moderate/strong evidence. Route review (or mid-confidence) to a human or stronger judge. Block on contradiction, missing evidence, or low confidence—and recalibrate thresholds when judgments collapse without real sources.

Can I bring my own API key?

Yes. Try the free demo above without signing in. To run it live on your own text, sign in with Google and connect a Flatkey or OpenRouter key (a quick test call runs when you save it). Manage or delete it anytime under Dashboard → BYOK. Keys are stored encrypted on the server, used only for runs you trigger, and never sent back to the browser. Need a Flatkey key? Get one for Jev 1.13 on Flatkey.

Is this the official TypeSafe Jev product page?

No. jev-llm.com is an independent research and practice site. Verify pricing, models and terms at the original TypeSafe sources.

Sources

Seen on X
Independent-site note: jev-llm.com is an independent research and practice site. It is not the TypeSafe AI official site. Verify models, pricing and terms at the original source.