Development & Automation

Liquid AI d1: The First Decision Model to Beat Jev, and How to Use the API.

A look at Liquid AI d1's three question types, how to use the API, the Hugging Face Decision Index comparison, and the decision model trend after Jev, from OpenAI to Ollama.

· Huuush

Liquid AI d1: The First Decision Model to Beat Jev, and How to Use the API

Key takeaways

  1. 1Liquid AI d1 is a decision model that takes a state and a question and returns Noul, Choice, and Score probabilities.
  2. 2In Liquid AI's reproduction of Decision Index 0.2.1, d1 scored 1.0 point higher overall than Jev 1.13.
  3. 3Create an API key, specify d1:free, and call it through the System One API or the TypeSafe SDK.

It really is all turning into Jev. After OpenAI released its GPT-6 Luna-based Decisions API, Liquid AI announced d1, its first decision model, on September 30 at 3:35 AM (KST). d1 does not generate long text; it classifies, selects, and scores among set options, and its output tokens are 0. Liquid AI says d1 is the first model to beat Jev on the Hugging Face Decision Index.

Chart comparing Hugging Face Decision Index scores by area for Liquid AI's first decision model d1 and Jev 1.13
Source: X @liquidai

What Liquid AI d1 is: a decision model that returns decisions instead of sentences

d1 takes a state and a question and returns the probabilities of preset answers in a single call. It does no ordinary text generation, so the output_tokens value in the official example response is 0.

Liquid AI says d1 leads in multilingual evaluation, is more robust against prompt injection, and handles long inputs better. It also presented fast, structured decision-making in software environments as a use.

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Source: X @liquidai

First to beat Jev on the Hugging Face Decision Index

In the comparison table Liquid AI published, d1 scored higher than Jev 1.13 in three of five areas: Arts, Language, and Retrieval. Jev led in Tools and Knowledge, and the overall Decision Index is 58.9 for d1 and 57.9 for Jev.

AreaBenchmarksd1Jev 1.13Difference
Arts745.537.7+7.8
Language1067.662.0+5.6
Retrieval660.755.4+5.3
Tools574.175.1−1.0
Knowledge1043.351.3−8.0
Decision Index5 areas58.957.9+1.0

As noted at the bottom of the chart, these values are Liquid AI's reproduction of Hugging Face Decision Index 0.2.1. You can see the evaluation setup on the Hugging Face Decision Index leaderboard.

Three question types: Noul, Choice, Score

TypeWhat it returnsExample
NoulYes/no probability (0 to 1)Is this message spam?
ChoiceOne named option, with a probability for each option and a confidenceWhich department will handle this inquiry?
ScoreThe probability-weighted position on an ordered rubric and the probability of each levelHow urgent is this request?

The answer to each question comes back in a fixed type. You can also put several questions of different types in one request and process them together.

How to use Liquid AI d1: from getting an API key to your first call

  1. Sign up at console.liquid.ai and join an organization.
  2. Go to API Keys in the Dashboard.
  3. Create a key and copy it. The key starts with liquid_, and you keep it in an environment variable.
export LIQUID_API_KEY="liquid_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"

This is the first-call example from the official docs.

curl -s https://api.liquid.ai/decisions/v1/systemone \
  -H "Authorization: Bearer $LIQUID_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "d1:free",
    "state": "I have been waiting over three weeks for my order and nobody has responded to my emails. This is completely unacceptable.",
    "questions": {
      "is_complaint": {
        "type": "noul",
        "instructions": "Is this message a complaint from the customer?"
      }
    }
  }'

The noul value of 0.999 in the response is the probability that the message is a customer complaint, and output_tokens is 0.

{
  "model": "d1:free",
  "answers": {
    "is_complaint": {
      "type": "noul",
      "noul": 0.999
    }
  },
  "usage": {
    "input_tokens": 84,
    "output_tokens": 0
  }
}

Install the Python SDK with pip install typesafe-sdk and the TypeScript SDK with npm install @typesafe-ai/sdk. Both SDKs use TypeSafeClient, and you set the base URL to https://api.liquid.ai on the same client as Jev.

Liquid AI researcher Maxime Labonne introduced the d1 checkpoint as free to try, comparing decision models to the BERT days of 2020.

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Source: X @maximelabonne

What to use it for: a rule for moving LLM calls to d1

The decision model docs list classification, routing, scoring, triage queue cleanup, content moderation, guardrails and safety checks, replacing an LLM judge, approving agent tool calls, and model routing as good fits. The rule is simple. If the answer is one of N options you set in advance, use a decision model, and if you need to write new sentences, use a language model.

ComparisonLanguage model callDecision model
OutputGenerated tokens to parseA decision with probabilities
LatencyGrows with output length and reasoningLow and predictable
Output tokensEven a one-word answer uses tokens0
UncertaintyNone, or the model reports a number itselfCalibrated probabilities on every answer
Schema errorsBroken JSON can appearReturned in a fixed format
Multiple decisionsSequential callsProcessed in parallel in one call

Language models handle tasks that need new sentences, such as writing, summarization, code generation, open-ended question answering, multi-turn conversation, and multi-step reasoning.

Demo: Road Decider, where d1 and Jev compete

Road Decider is a pixel-art racing game about surviving on a three-lane road. Two cars run the same road, you have three lives, and there is no finish line. Depending on game speed, it sends d1 a Choice question 2 to 5 times per second to pick one of LEFT, CENTER, or RIGHT.

Road Decider pixel racing game screen showing d1 and Jev each picking a lane, with confidence bars
Source: GitHub Liquid4All/cookbook

In You vs d1 mode, you move yourself with the arrow keys and start with Enter. Jev vs d1 mode uses an OpenRouter key, and the default Jev model is typesafe/jev-1.13. You need Node.js 18 or later and a Liquid API key.

git clone https://github.com/Liquid4All/cookbook.git
cd cookbook/examples/road-decider
cp .env.example .env
# Edit .env: add LIQUID_API_KEY, and optionally OPENROUTER_API_KEY
npm install
npm run dev

After starting the dev server, open the local address to begin racing.

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Source: X @liquidai

Two weeks after Jev: OpenAI, Ollama, and Liquid AI too

Jev was released on September 16 at 3:17 AM (KST). The new approach of a decision model that makes set choices quickly drew attention.

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Source: X @CompleteSkeptic

On September 29, OpenAI released the GPT-6 Luna-based Decisions API at DevDay. We covered the details in OpenAI Decisions API: Two Weeks After Jev, GPT-6 Luna Picks an Option in 0.15 Seconds.

On September 30 at 1:25 PM (KST), Ollama announced support for local decision models. You start with ollama pull nimble and use the local /v1/systemone API. Nimble, Tev1 4b, and Tev1 0.8b are available, and you can apply them to ticket triage, model routing, and content moderation. You can find details on the official Ollama blog and in the docs.

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Source: X @ollama

The same day, Liquid AI also released its first decision model, d1. Just two weeks ago Jev was a novelty, and now everyone from OpenAI to Ollama to Liquid AI is moving the same way.

Sources

Frequently asked questions

What kind of model is Liquid AI d1?
It is a decision model that takes a given state and a question, classifies, selects, and scores in Noul, Choice, and Score types, and returns the probabilities of the set outcomes.
What are d1's Noul, Choice, and Score?
Noul returns a yes/no probability, Choice returns the named option and a probability for each option, and Score returns the probability-weighted position on an ordered rubric and the probability of each level.
How do I get started with the Liquid AI d1 API?
Create a key that starts with liquid_ under Dashboard > API Keys at console.liquid.ai, store it in LIQUID_API_KEY, and send a request to https://api.liquid.ai/decisions/v1/systemone with model d1:free.
When do I use a decision model versus a language model?
If the answer is one of N set options, use a decision model, and if you need new sentence generation or open-ended answers, use a language model.

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