What is Jev / System One?

Jev is TypeSafe AI’s first public System One model (Diogo Almeida, ex-OpenAI). It takes software state plus typed questions and returns calibrated probabilities. Named after Jevons; System One after Kahneman. AItier (https://aitier.app/jev/) is a personal discussion wall with a Models Rank chip id jev — not TypeSafe’s site.

No. Jev is built for structured judgments inside software, not chat text. TypeSafe documents three question types: Choice, Score, and Noul (yes/no probability). TypeSafe claims ~70–500ms, cheap input, and free output; those are vendor claims, not an AItier ranking. TypeSafe also says it “can’t hallucinate” because outputs are typed rather than free-form language — that is not a scientific guarantee of factual correctness.

How do I rank Jev on AItier?

Open https://aitier.app/models, find the Jev (System One) chip (id jev), drag it onto S+ through F, then export a PNG. That is your personal list — whether a decision model belongs next to chat models is the argument. Optional: https://aitier.app/predict/ .

Is this official TypeSafe?

No. AItier is a personal AI model tier list product. aitier.app is not TypeSafe’s website and is unrelated to aitier.net. The /jev/ page and Models Rank are not an official TypeSafe site, ranking, or evaluation.

Where are the posts from?

The wall embeds public X posts about Jev, use cases first, then TypeSafe official posts, then explainers. Each slot is hardcoded in the HTML with data-tweet-id (curated in /jev/posts.json). Each slot links back to the original post. Not invented quotes.

AItier — TypeSafe Jev (System One) ranking

Use cases first — then TypeSafe official, then explainers. Public X posts, hardcoded in this HTML.

Use cases

preview of how fast browser use can be

powered by typesafe's jev and opencode's browser use cli
— dax (@thdxr) @thdxr · September 16, 2026

woah - maybe browser use is the first killer use-case for jev
— Steve Krouse (@stevekrouse) @stevekrouse · September 16, 2026

TypeSafe AIのJev、前に入力上限とかを測ったんですが、今度は「安全判断」で試してみました。

文章の有害判定と、AIが生成したコマンドを実行前にチェックする用途です。
— kiarina (@kiarina37) @kiarina37 · September 17, 2026

jev + kernel browser use demo

pretty freaking cool! so fast!

try it yourself:
— Steve Krouse (@stevekrouse) @stevekrouse · September 16, 2026

【注目】Browser Use×TypeSafe「Jev」でブラウザ操作AIが爆速化

今一番バズっている話題のサービス。速く使いたい、、、

Google Flightsの片道検索を自動操作だけで完走するデモが話題に

・所要時間はわずか7.1秒
・判断レイテンシは中央値150〜300ms
・出発地/到着地/日付など5ステップを自律実行
— チャエン | デジライズ CEO (@masahirochaen) @masahirochaen · September 17, 2026

Jev 这个 waitlist 还是很给力的，昨天申请，今天就能用上。

给已经拿到 API、但还不知道怎么玩的人整理了一份 Awesome Jev，目前我能确认到的 Jev 项目基本都在这里：

1. jev-ultrafast
Browser Use 做的高速浏览器 Agent。
— 思维怪怪 (@0xLogicrw) @0xLogicrw · September 17, 2026

okay so browser use is a legitimate use case

agent-browser <> Jev loop

goal: wiki race from 'Coffee' to 'Artificial Intelligence'
— joogie (@princecaarlo) @princecaarlo · September 16, 2026

判断専用モデル TypeSafe AI（Jev）に、サポート問い合わせを投げてみた。

同じ state に対して、3つの質問タイプを1コールで並列実行。

Choice → 担当 returns（confidence 1.0）
Score → 苛立ち 1.88 / 2（強い苛立ち寄り）
Noul → 返金要求 0.98

入力 $0.042/MTok・出力無料。

#TypeSafeAI
— Hatch (@HatchSystem) @HatchSystem · September 17, 2026

Official

JEV LIVES
— TypeSafe AI (@typesafeai) @typesafeai · September 16, 2026

Look at Jev hitting 100% accuracy for @vercel
— TypeSafe AI (@typesafeai) @typesafeai · September 16, 2026

Check your emails! We just let off a huge batch of people from the Jev waitlist. Getting as many people off waitlist today as possible.
— TypeSafe AI (@typesafeai) @typesafeai · September 16, 2026

Jev is now available on the @vercel AI Gateway https://vercel.com/ai-gateway/models/jev
— TypeSafe AI (@typesafeai) @typesafeai · September 17, 2026

Explainers

ChatGPT 联合发明人创办的 TypeSafe AI 正式发布了一种全新类别的 AI 模型："System One 模型"，以及该类别下的第一个模型 Jev。和现有的大语言模型不同，Jev 完全放弃了文本生成能力，专门为软件内部的快速决策而设计：输入非结构化数据，输出带有校准概率的类型安全结构化结果。
— 宝玉 (@dotey) @dotey · September 16, 2026

The interesting part about cheap AI isn’t the price.

It’s what software can do when decisions become fast and reliable enough to act on.

TypeSafe AI just introduced Jev, its first public System One Model. It’s not an LLM wrapper, it’s an API for developers that returns composable, structured decisions with probabilities and confidence scores.

At ~100x faster and cheaper than LLMs, real-time apps and huge datasets become much more practical.

Basically: computers can talk to each other in English without waiting for each other to finish. Curious to see what gets built with that.
— Liam | AI Tools & News (@ottleyai) @ottleyai · September 15, 2026

高速な判断に特化したAI - TypeSafe「Jev」と System One Model
— 布留川英一 / Hidekazu Furukawa (@npaka123) @npaka123 · September 16, 2026

TypeSafe AI just launched JEV which is its first “System One” model built to answer structured questions in parallel instead of generating text token by token.

That opens the door to AI systems that can return usable decisions with confidence scores.
— Shay Boloor (@StockSavvyShay) @StockSavvyShay · September 15, 2026

TypeSafe AI has introduced its first model named Jev - a small and customizable System One decision model.

Not being an LLM, Jev can’t reason or write explanations; it generates a fast judgment with calibrated probabilities and a confidence score.

Anything heavier gets split into separate questions and recombined in code.

TypeSafe reports a response time of approximately 150ms per call, at around 100x lower cost and faster responses than LLMs, with pricing at $42 per billion input tokens and free output.
— 🚨 AI News | TestingCatalog (@testingcatalog) @testingcatalog · September 15, 2026

FAQ

What is Jev / System One?: Jev is TypeSafe AI’s first public System One model. It takes software state plus typed questions and returns calibrated probabilities. Named after Jevons; System One after Kahneman. This page is a crawlable landing plus a wall of public X posts, with a pointer to rank chip jev on your personal tier list.
Is Jev a chat LLM?: No. It is built for structured judgments inside software, not chat text. TypeSafe documents Choice, Score, and Noul (yes/no probability). Speed/cost and “can’t hallucinate” (typed output, not free-form language) are vendor claims — not an AItier score, and not a guarantee the chosen option is factually right.
How do I rank Jev on AItier?: Open Models Rank, find Jev (System One), drag it onto S+ through F, export a PNG. Your list — including whether a decision model belongs next to chat models. Optional: Predict.
Is this official TypeSafe?: No. AItier is a personal AI model tier list. Not TypeSafe’s site, not an official ranking or eval. Unrelated to aitier.net.
Where are the posts from?: Public X embeds, use cases first, then official, then explainers. Hardcoded data-tweet-id in this HTML (curated in /jev/posts.json). Each slot links to the original post.