Article
CommunityJev Guides & Articles
Jev (AI model)
Wikipedia's article on Jev: TypeSafe AI, the September 15, 2026 early-access release of jev-1.13.0, the Choice, Score, and Noul primitives, RLCD training, and the unpublished weights and technical paper.
- Format
- Article
- Reading time
- 3 min
- Published by
- Community
- Last verified
- Sep 2026
Used inJev for Software & DevTools
Highlights
- Released September 15, 2026 in limited early access as jev-1.13.0, alongside a $40 million seed round led by DCVC.
- Founded in 2024 by Diogo Almeida, Erik Gafni, and Sasha Sheng; Almeida spent about four years at OpenAI on RLHF, InstructGPT, ChatGPT, and GPT-4.
- Lists Choice, Score, and Noul primitives and says answers cannot fall outside the supplied schema; TypeSafe presents this as eliminating type errors.
- States TypeSafe has not published Jev's exact architecture, weights, or a technical paper; outside observers suggest an open-weight LLM base.
- Names RLCD (Reinforcement Learning for Calibrated Decisions), trained on synthetic data with probabilities optimized against outcomes, not human preference.
Watch out
A community-edited encyclopedia entry built from vendor posts and press coverage; its speed and cost figures are TypeSafe's self-tested claims, which the article notes likely sit at the high end.
Questions about this entry
Short answers drawn from the linked project or page.
No. The article states TypeSafe has published no exact architecture, no weights and no technical paper. It describes the model as transformer-based and trained only on synthetic data, and notes that outside observers have suggested it may be built on an open-weight LLM.
Hosted access is the only documented route. The article lists the license as proprietary and the release as limited early access, with the model returning typed values, probability estimates and confidence scores to software rather than downloadable weights.
No. Jev is described as a discriminative model for classification or regression that does not produce natural-language text, and whose output is meant to be read by software rather than a person. It only answers typed questions you define at prediction time.
No. The 70 to 500 ms end-to-end response times are TypeSafe's own figures, drawn from vendor posts and press coverage. The entry's own note is that such numbers likely sit at the high end of real-world performance, and no third-party benchmark appears on the page.
Limited early access on 15 September 2026, alongside a $40 million seed round led by DCVC. The stable release listed is jev-1.13.0, the license is proprietary, and it was developed in stealth for roughly two years beforehand.
Founded in 2024 by Diogo Almeida, Erik Gafni and Sasha Sheng. Almeida, the chief executive, spent about four years at OpenAI on RLHF, InstructGPT, ChatGPT and GPT-4 before leaving in 2024.
The System One model works on Reinforcement Learning for Calibrated Decisions, or RLCD. The name comes from 19th-century economist William Stanley Jevons, whose Jevons paradox describes how more efficient use of a resource can increase consumption.
Reactions & coverage
Posts, threads, and videos about this entry from around the web.
X: How the agent stack moved in Jev's first three days
YouTube: Diogo Almeida tells swyx what System One is, why RLHF failed his automation goal, and why AI should eventually disappear.
X: The 10-step roadmap, summarised
X: Giving your agents a decision brain
From the Jev guides
Original write-ups on what this entry is for.
From the Jev AI model community
Posts from builders shipping with Jev right now.