devwithjev
reading now views
Submit a build

JevX Evaluates Jev Fit in Codebases

JevX analyzes a codebase to find places where deterministic rules may be making semantic decisions and evaluates whether Jev is a good fit.

zepa@zepaui𝕏
Launching JevX — because AI shouldn’t tell you to use Jev everywhere. Though, I got early access to TypeSafe/Jev, and spent the last 5 days trying to answer a deceptively hard question: where does Jev actually belong in a real codebase? - After several failed approaches, pattern experiments, datasets, and studying and training with 44 open-source projects, After 4 versions, JevX v0.4.0 is the result — a tool that analyzes your codebase, finds places where deterministic rules may actually be making semantic decisions, and evaluates whether Jev is a good fit. JevX combines learned patterns, code
Sep 23, 2026X postsView on X
Zepa built it after getting early access to TypeSafe/Jev and spending five days exploring where Jev belongs in real codebases. The tool followed four versions and study and training with 44 open-source projects.

Also filed under Tools & apps

  • Jev: a "System One" model that only makes decisions, $0.042 per million tokens with output free. 40-second explainer of why it matters for automation

    Jev: a "System One" model that only makes decisions, $0.042 per million tokens with output free. 40-second explainer of why it matters for automation Jev launched on Sep 15 from TypeSafe AI (founder Diogo Almeida, ex-OpenAI, credited on ChatGPT/InstructGPT). It does not generate text; it returns typed decisions (Choice / Score / true-false) with confidence. Price is $0.042 per million input tokens, output free. In its first week it became the fastest-adopted model on Vercel's AI Gateway, TypeSafe paused signups on Sep 22, Browser Use released jev-ultrafast (a web agent where Jev picks each action; Google Flights search in 7.1 s), and jaredpalmer/kev is an Apache-2.0 clone built on Qwen3.5 you can run yourself. My take in the video: the expensive part of automation was never the writing, i

  • Untitled

    There's a new AI model that refuses to talk. While everyone debates what a "decision model" is even for, builders already shipped the answer. 7 things people built with Jev in 9 days. Number 5 broke my brain 👇

  • Untitled

    I loved this idea so much that it deserves a share ❤️ I recently asked people to share what they’ve built with JEV, and then this guy 👤 shows up with an entire website dedicated to different JEV use cases! That’s honestly pretty cool. If you’re curious about JEV and want to see how it can actually be applied, definitely check this out. Huge shoutout to Animesh Mishra (@thatcasualvc) for the wonderful share 🙌 This is exactly the kind of stuff I love seeing from builders. 🚀

  • I built a Jev-based model router for Pi for automatic model selection

    I built a Jev-based model router for Pi for automatic model selection When Jev came out, one of my first thoughts was: could something this fast and cheap pick which model should handle an agent’s next turn? So I built plugin for Pi that uses Jev to choose the model and thinking effort. The idea is to send routine work to cheaper models and reserve the expensive ones for harder tasks. In Pi, the model mappings are configurable, and you can pin a model when you disagree with the router. I’ve been using them for a few days, and so far they’ve been working well for me. In my own evaluation, routed usage came to $141 at list prices versus an estimated $166 for Opus 5.5 on every request - about 15% less. That’s one developer’s data, though. The baseline is a pricing comparison, not a separate