Decision-model landscape

System One Models & Typed Decision Engines

A System One model, or typed decision engine, answers typed questions about some input and returns probabilities instead of generated text. TypeSafe Jev named the category on September 15, 2026, and a wave of open models followed within days. This table tracks them side by side, with the facts each project publishes.

Checked against each project’s own pages on Oct 2, 2026.

How accurate are they on the same questions? See the System One benchmark

ModelApproachSizeLicenseRuns onJev APILanguagesSource
TypeSafe Jev

by TypeSafe AI

The hosted model that introduced the System One name and the choice, score and noul question types. Generally available and billed per token.

Hosted modelUndisclosedProprietaryTypeSafe cloud onlyReference APIProvider-dependentTypeSafe docs
Liquid AI d1

by Liquid AI

Liquid AI launched the hosted d1 on September 29, 2026 with a free tier (model name d1:free). On October 5 it released open weights on Hugging Face: d1-3B (text and images, built on LFM2.5-VL-3B, 32K context) and d1-omni-600M (text with images or audio). Liquid reports d1-3B at 48.57 on Decision Index 0.2.1, the best score under 10B (self-reported).

Hosted model, plus open-weight modelsd1-3B (3.1B), d1-omni-600M (587M); hosted d1 undisclosedLFM Open License v1.0 (open weights); hosted d1 proprietaryLiquid API, or your own hardware (d1-3B: 8 ms a decision on an RTX 4090, 30 ms on an Apple M5 Pro, per Liquid)Hosted: yes, POST /decisions/v1/systemone, works with the TypeSafe SDKs; open weights: same question format through Transformers16 listed on the d1-3B card; d1-3B also reads images, d1-omni-600M images or audioLiquidAI/d1-3B on Hugging Face
OpenAI Decisions API

by OpenAI

Announced at DevDay on September 29, 2026 and in public beta since October 6: $0.10 per 1M input tokens, with no charge for output or cache. Returns probabilities and a confidence for choice and score answers; OpenAI says it answers about 10x faster than the Responses API.

Hosted modelUndisclosed (a version of GPT-6 Luna)ProprietaryOpenAI API onlyNo, its own endpoint (POST /v1/decisions) with predicate, choice and score questionsNot stated; accepts text or imagesOpenAI Decisions guide
Microsoft-Decision-1

by Microsoft

Announced October 9, 2026 and available in Microsoft Foundry (Preview in the catalog) at $0.042 per 1M input tokens, the same as Jev, with output free. Microsoft reports the highest accuracy across 36 benchmarks and about 35x lower median latency than GPT-6 Sol (self-reported); Clef is not in its comparison, and Jev was added only in a later update.

Hosted model (post-trained Qwen3.5-9B)9BProprietaryMicrosoft Foundry onlyJev request body (noul, choice, score) at its own Azure endpoint, /providers/microsoft/v1/systemoneNot stated; text or JSON only, up to 32,768 tokensMicrosoft launch post
Cloudflare Clef

by Cloudflare

Released October 1, 2026 with open weights on Hugging Face and hosted on Workers AI. On October 9 Cloudflare added Clef-Omni (audio input, $0.15 per 1M input tokens) and cut Clef-Flash to $0.038, below Jev, with a 24,576-token hosted context. Cloudflare reports Clef leading 7 of 10 decision benchmarks against Jev, and Clef-Flash at 38.8 ms median latency (self-reported).

Fine-tuned Qwen models with a joint decision head27B (Clef) / 9B (Clef-Flash) / 30B-A3B (Clef-Omni)Apache 2.0Workers AI, or your own large GPU (tested on one H200)Yes, Jev / SystemOne request and response formatNot stated; accepts text, JSON, images and video, and Clef-Omni also audioCloudflare/clef on Hugging Face
Laya

by Convai Innovations

Non-autoregressive choice, score and noul heads on ModernBERT and mmBERT encoders, with a Router, fine-tuning and many community runtimes.

Trained encoder with decision heads322M / 421MApache 2.0CPU, CUDA, Apple SiliconYes, through laya-serveEnglish, plus a 100+ language checkpointNandhaKishorM/laya
Kev

by Jared Palmer

Small Jev-like models on Qwen3.5 and Qwen3.8 bases. Each checkpoint ships a fitted temperature, and a fine-tune and deploy loop runs on Modal.

Fine-tuned Qwen models0.8B / 4B / 9B / 27BApache 2.0Apple Silicon Mac (0.8B) up to one 80 GB GPU (27B)Yes, the TypeSafe SDK works unchangedNot statedjaredpalmer/kev
OpenDecider

by Manjunath Shiva

Distilled from two open teacher models. The 400M nano model scores 0.796 on the typed-decisions benchmark, against 0.766 for Laya's fine-tuned checkpoint and 0.754 for Jev (author's measurements). Early release, updated often.

Trained encoder (nano); fine-tuned Qwen (small, medium)~400M / 4B / 30B MoEApache 2.0CPU, CUDA, Apple Silicon (MLX builds); 30B needs several NVIDIA GPUsYes, `opendecider serve` (0.2.0+): POST /v1/systemone and /batchEnglish (only English evaluated so far)manjunathshiva/opendecider
Decider

by Mapika

One-pass typed decisions with calibrated probabilities, trained on public data and labels from a local Qwen3.5-27B teacher. Choice supports 2 to 255 options.

Fine-tuned Qwen models2B / 4B / 35B MoEApache 2.0Local GPU, vLLM servingYes, a /v1/systemone endpointNot statedMapika/decider
Von

by wfzyx

Built on ModernBERT-Large. Version 1.2 scores each option independently, so the answer no longer depends on the order the options are listed in.

Trained encoder, non-autoregressive395MApache 2.0Local CPU or GPUYes, a /v1/systemone serverEnglishwfzyx/von
Bespoke Nimble

by Bespoke Labs

Publishes the data curation, training and serving recipe behind Bespoke-Nimble-9B, which now takes 8,192-token inputs and up to 255 choices per field.

Fine-tuned model with training recipe9BNot stated in the repositoryApple Silicon, NVIDIA GPUNo, its own schema formatNot statedbespokelabsai/nimble
SemIf (formerly OpenJev)

by TheoLeeCJ

Scores typed options directly from a frozen open model with no answer text or JSON parsing, with per-workload temperature calibration.

Training-free, reads option probabilities from open LLMsDepends on the model (2B to 27B tested)MITRTX 3090, Apple Silicon, browser (WebGPU demo)Reproduces the interface patternDepends on the modelTheoLeeCJ/SemIf-OpenJev
Rizzo Flow

by Rizzo AI Academy

A local take on Jev with a LoRA fine-tune of Spark-X2.5. The project reports 0.648 on typed-decisions against 0.727 for Jev, and notes that probabilities are uncalibrated unless you calibrate them on your own data.

Fine-tuned LLM (Spark-X2.5) on llama.cpp1.7B / 4BApache 2.0llama.cpp: CUDA, Metal, Vulkan, ROCm, SYCL or CPUYes, POST /v1/systemoneNot statedRizzo-AI-Academy/rizzo-flow
AnyJev

by Nokia Applied Research

Turns an existing LLM into a Jev-style decision model by reading its hidden states, with debiasing and calibration levels and no task-specific training.

Training-free library over existing LLMsDepends on the modelApache 2.0Hugging Face models, vLLM servingServes its own decision endpointDepends on the modelnokia-applied-research/AnyJev
NanoJev

by TianyuCodings

A compact replica with an end-to-end training pipeline, evaluated on game tasks such as ViZDoom, a maze and Snake against Jev.

Small parallel decision model0.6BMITLocal GPUNot statedNot statedTianyuCodings/NanoJev
Tev1-4B-experimental

by Together AI

An experimental supervised fine-tune of Qwen3.5-4B released on September 23, 2026, with the data recipe and a guide to training a similar classifier.

Fine-tuned LLM, answers with one option letter4BWeights license being finalized; code MITTogether API, or self-hosted Transformers and GGUFNo, chat completions with 2 to 24 optionsNot statedtogethercomputer/Tev1-4B-experimental
GLiNER2.5-Decide

by Fastino

Takes label sets at call time and scores several heads in one pass. Built for operational decisions such as intent, routing, sentiment and priority.

Encoder classifier340M (also 1B, and 287M multilingual)Apache 2.0CPU or GPU with the gliner2 packageNo, its own classify_text APIEnglish, plus a multilingual variantfastino/GLiNER2.5-Decide
OpenThai-SystemOne

by iApp Technology

A Qwen3.5-0.8B text tower whose output head is replaced by a 256-way slot softmax, continued-pretrained on Thai.

Fine-tuned model with a slot head0.8BApache 2.0CUDA, MPS, CPUYes, mirrors POST /v1/systemoneThai, Englishiapp-technology/openthai-systemone
djev (DiffusionGemma-Jev)

by mmastrac

Reads Jev-style decisions from DiffusionGemma, a discrete diffusion model, in one denoise step through vLLM. The djev-dev fork adds native image inputs and live camera sampling.

Training-free, reads decisions from a diffusion LLMDiffusionGemma (26B-A4B in the DGX Spark recipe)Apache 2.0NVIDIA GPU with vLLMYes, POST /v1/systemoneNot statedmmastrac/djev
Jev-Omni

by akhilaaa3

A decision classifier for text, images, audio and video, fine-tuned on 30,000 questions: a probability per option instead of an explanation. Reports 86.15% on matched JevBench groups (self-reported).

Fine-tuned multimodal model12B (Gemma 4 12B)Apache 2.0NVIDIA GPUNot statedNot statedakhilaaa3/Jev-Omni
Open-Jev

by Zefan Cai

Scores the candidates you supply for choice, noul and score questions without generating an answer, using a trained head on top of Qwen3.5.

LoRA adapter + scalar decision head2B, 9B, 27B (Qwen3.5)Apache 2.0NVIDIA GPUYes, a local /v1/systemone serverNot statedZefan-Cai/Open-Jev
JevK5

by alibiserikbay

Qwen3.5-4B with a merged LoRA, read out with the SemIf protocol and one calibration temperature. Questions with more than 16 options are read in several passes.

Fine-tuned LLM with calibrated letter readout4B (Qwen3.5-4B)Apache 2.0Local GPUYes, TypeSafe-style /v1/systemone runtimeEnglishallebee/jevk5
open-jev-deberta-v3-large

by kotoba-lang

An independent reproduction of the Jev interface: choice (up to 255 options), score (2 to 10 levels) and noul in one forward pass, measured on public gold labels.

Trained encoder, non-autoregressive434M (DeBERTa-v3-large)Apache 2.0Local CPU or GPUNo, a Python libraryEnglishcom-kotobalabs/open-jev-deberta-v3-large
AgentJev

by malevrigns

The language-model head is removed and a candidate head scores the options. The published checkpoint judges whether a coding task is actually finished.

LLM backbone + order-invariant candidate head0.6B (Qwen3-0.6B)Apache 2.0Local CPU or GPUNo, its own server and clientEnglish, Chinesemalevrigns/agent-jev
Jev-Style

by chaoliangUNSW

GGUF decision models that return calibrated option probabilities from a single token. v3 reports 79.2% on 2,000 typed decisions and takes 25,600-token inputs.

Fine-tuned LLM, one-token decision (GGUF)0.8B (v3); 2B (v1)Apache 2.0llama.cpp, LM Studio (CPU or GPU)No, chat completions with logprobs51 (v3)jevstyle.com
Anarkali

by ToufiqQureshi

A 68M encoder that beats Jev on the public typed-decisions benchmark (74.0% vs 72.7%) and comes within 2.6 points of Laya at a sixth of the size, with the lowest calibration error of the three (author-reported).

Trained encoder (Ettin), non-autoregressive68MApache 2.0CPU or GPU via a single 273 MB ONNX fileYes, POST /v1/systemoneEnglish onlyToufiqQureshi/anarkali
Jeeves

by PostHog

Thinks before it answers: 0.935 on the public JevBench items vs 0.866 for Jev (0.865 vs 0.730 on the hard tier), at about 0.3 s per request without thinking and a 3.3 s median with it on one H100. Jev still leads on MMLU-Pro (author-reported).

Fine-tuned LLM (LoRA + pointer head) that reasons before deciding9B (Qwen3.5-9B)MIT code, Apache 2.0 weightsCUDA GPU (FP8 kernel needs Hopper)Yes, a local /v1/systemone serverNot statedPostHog/jeeves
OpenJev-4B

by ejhshen (Junhao Shen)

Options and criteria are inputs, so the output follows whatever candidates a request supplies, and reordering them does not change the answer. Trained with SFT then RL on the public OpenJevData-140k set; training code included.

LLM backbone + option-set decision head, non-autoregressive4B (Qwen3.5-4B)MITCUDA GPUYes, a local /v1/systemone serverNot statedejhshen/OpenJev

Which one fits your situation?

You already call Jev and want to self-host

Start with a model that serves POST /v1/systemone: Laya (laya-serve), Kev, Decider, OpenDecider, Von or OpenThai-SystemOne. Existing client code points at the new base URL.

CPU-only servers or low latency

Encoder models are the smallest here: Laya (322M to 421M), Von (395M) and GLiNER2.5-Decide (340M).

Highest accuracy on a large GPU

The larger fine-tuned LLMs, such as Kev-9B or Kev-27B, Decider 35B MoE and Bespoke Nimble 9B, or Jeeves 9B if a few seconds of reasoning per request is acceptable. Measure on your own data before switching.

Non-English input

laya-multilingual covers 100+ languages; OpenThai-SystemOne targets Thai and English; GLiNER2.5-multi-Decide is Fastino’s multilingual variant.

A hosted API other than Jev

Liquid AI d1 speaks the same System One API and has a free tier; switch by changing the base URL and model name. Cloudflare Workers AI serves Clef and Clef-Flash with the same request body but its own URL and API token, and you can also run their weights yourself. Microsoft-Decision-1 on Microsoft Foundry takes the same request body at its own Azure endpoint, for the same price as Jev ($0.042 per 1M input tokens). The OpenAI Decisions API is open to all developers in public beta ($0.10 per 1M input tokens), but uses its own request format.

No training at all

Training-free approaches such as AnyJev and SemIf read decisions from an open LLM you already run.

Replacing Jev?

See which open models and servers accept Jev requests unchanged, and what switching involves.

Compare Jev alternatives

What makes a System One model different?

A System One model reads a state, such as a ticket, an email or some JSON, plus a set of typed questions. It returns an answer and a probability for every allowed option in a single pass, with no free-form text to generate or parse.

The projects above get there in different ways. Some train an encoder with decision heads (Laya, Von), some fine-tune an open LLM (Kev, Decider, Nimble, Tev1, Rizzo Flow), and some read decisions out of an existing LLM without training (AnyJev, SemIf). That changes the model size, the hardware you need, and how the probabilities are calibrated.

Benchmarks in this space are young and mostly self-reported, on different datasets. Compare deployment, calibration, language coverage, option count and latency, and test on your own labelled data before choosing.