Ex-OpenAI researcher launches Jev, a System 1 decision model, now open to all

Former OpenAI researcher Diogo Almeida — who worked on RLHF/InstructGPT instruction-following research in the ChatGPT era and has been called a "co-inventor of ChatGPT" by many — has ended two years of stealth startup work to release Jev, the first "System 1" model from his new company TypeSafe AI, drawing wide attention. The model is the complete opposite of the conversational AI route: no chatting, no coding, it only makes semantic judgments among given options, claiming to be 20–200x faster, 40–400x cheaper than LLMs, and hallucination-free. Jev has now dropped its waitlist and is fully open, with new users getting $5 in credits (about 120 million tokens).

Confirmed

• Jev is positioned as "an AI model built for fast, structured decisions in software": given a context and explicit options, it outputs a Choice, per-option probabilities, and a confidence level, returning within hundreds of milliseconds at under one ten-thousandth of a dollar per call (@xiaohu)
• Almeida proposed the concept of "composable intelligence" along with a self-described new training method, RLCD, and questioned "why superhuman chat models haven't delivered AGI" — one answer is to bypass the old path of "making a model play the consumer and then parsing text" (@MaryamMiradi, @soumitrashukla9)
• The official site offers about 10 demos, including playing DOOM and Minecraft with AI, browser agents, and LLM-as-judge scenarios (@FinanceYF5)
• Jev is now open to everyone, with $5 in free credits (@机器之心)
• swyx's Latent Space podcast will release a conversation with him (@altryne retweet)

Unconfirmed

• The "200x faster, 400x cheaper" claims come from the launcher; Fireship's video also notes the model "can't write code yet claims to be 200x faster" — no independent third-party verification has appeared
• "Co-inventor of ChatGPT" is Almeida's own account, with the community mostly citing his RLHF/InstructGPT work when repeating it

Why it matters

• Jev represents a differentiated route of "skip generation, judge directly," called by developers like pkiv "one of the biggest unlocks for fast, cheap browser agents"
• @xiaohu sums it up as "an intelligent if-branch with common sense," well suited to the many low-cost intermediate decision nodes in agent workflows; if the performance claims hold, it could reshape the cost structure of agents

2026-09-21 ~ 2026-09-22 · 14 related posts

Full story(4 episodes)→

• Episode 1: Indie researcher says he built Jev's non-autoregressive decision model a year earlier(2026-09-20, 6 posts)
• Episode 2: ianand's Thought Experiment: Jev, a Decision-Only AI From a Parallel Universe(2026-09-20, 9 posts)
• Episode 3: Ex-OpenAI researcher launches Jev, a System 1 decision model, now open to all(2026-09-21, 14 posts)
• Episode 4: Jev: A Decision-Only AI Model Returns Probabilistic Answers in 200ms(2026-09-21, 2 posts)

• Jev, built by an RLHF/InstructGPT veteran, targets machine decisions with new RLCD training — MaryamMiradi · 2026-09-21
• [source] ChatGPT co-inventor launches Jev, claiming 20-200x speed and 40-400x cost gains — BLUECOW009 · 2026-09-21
• ChatGPT co-inventor launches Jev, a decision-optimized model claiming 20-200x speed and 40-400x cost gains — soumitrashukla9 · 2026-09-21
• ChatGPT co-creator launches Jev, a free AI that never writes a word—only decides — PrajwalTomar_ · 2026-09-21
• "ChatGPT co-inventor" launches Jev, claiming 20-200x faster and 40-400x cheaper frontier model — altryne · 2026-09-21
• Jev, from a ChatGPT co-creator, makes AI decisions 200x faster and 400x cheaper — rubenhassid · 2026-09-21
• [source] Judgment-only model Jev opens to all with $5 free credit, sparking calibration debates — 机器之心 · 2026-09-21
• Jev guide: the System-1 model that only judges and never writes — xiaohu · 2026-09-21
• ChatGPT co-inventor launches decision-making AI, claims 20-200x faster decisions — FinanceYF5 · 2026-09-21
• TypeSafe AI launches Jev, a "System One" decision model 100x faster than LLMs, no hallucinations — rseroter · 2026-09-21
• Ex-OpenAI researcher's Jev: a System 1 model claiming 200x speed and no hallucinations — Fireship · 2026-09-22
• TypesafeAI's Jev: a new model class built for fast, structured software decisions — Hacubu · 2026-09-22
• Jev-style models called a major unlock for fast, cheap browser agents — multiply_matrix · 2026-09-22
• [source] TypeSafe CEO on Jev: machine-native models for code, RLCD over RLHF — Latent Space · 2026-09-22