Jev-pilled

My Jev pill · three AI models · 300 use cases

How could a tiny decision model be so interesting?

Ever since Jev was released, I’ve been fascinated by where all it can be used. Any use case comes in and my first thought is: hey, why don’t we use Jev over there? So this is me sharing my Jev pill with all of you. Hopefully you’ll see what I see in this model.

Try the live comparison → Run one question through OpenAI, Claude and Jev and see how they answer.

Here’s what I did. I shared the exact same questions with Grok, Claude and Codex, and asked each one for 100 places Jev could be used, with an example for every one. Below is what each of them kept telling me.

Claude Fable

Deep and specific

17 industries78 words / case25 multi-question cases

Stands out for

  • Concrete thresholds and the exact next step in every example
  • Healthcare depth: nine health-plan cases, from prior auth to CMS appeal clocks
  • An AI-governance section: judge cascades, guardrails, red-team grading

Watch for

  • Fewest industries of the three
  • Quotes vendor-reported speed and cost figures
Open Claude Fable’s version →

Codex Astra

Broad and careful

20 industries115 words / caseBest accessibility

Stands out for

  • Widest coverage, five cases in each of 20 industries
  • Every example labeled fictional, with keep-a-human-in-review framing
  • Skip link, screen-reader labels, live result count, print view, links to TypeSafe’s docs

Watch for

  • Leans on one question type (62 of 100 are Choice)
  • Longest read; examples start collapsed
Open Codex Astra’s version →

Grok

Compact and scannable

20 industries57 words / caseMost even mix

Stands out for

  • Shortest read; cards start collapsed so titles scan fast
  • Clickable industry filter, multi-select type filter and a Reset button
  • Most balanced use of the three question types

Watch for

  • Intro, industry list and first three cases match Codex Astra’s word for word
  • No dark mode; page is drawn by JavaScript, and search skips example text
Open Grok’s version →

Start here

What is Jev?

Most AI models write. Jev, from TypeSafe AI, decides. You give it some text and a question with a fixed set of possible answers. It picks one and tells you how sure it is. That’s the whole job.

Because it never writes, it is fast (around a fifth of a second in published tests) and cheap enough to run on every message, claim or output instead of a sample. The catch: it won’t explain itself, so your code, and sometimes a person, decides what to do with the answer.

Want the deeper take? Sebastian Raschka argues it’s more than a classifier, and that how well it generalizes across tasks is the real story: It’s Easy to Dismiss Jev as Just a Classifier →

Good at

  • Routing to the right team
  • Yes/no policy and evidence checks
  • Rating against a rubric
  • Gating risky actions

Not built for

  • Writing or summarizing
  • Math or new values
  • Images or audio
  • Explaining its answer
Your app gathers the text text + a question + the allowed answers Jev picks one · ~170 ms answer + probability “yes”, 0.96 Your threshold rule plain code, set per risk ≥ 0.9 in between ≤ 0.1 Act on it automatically Escalate LLM or a person Other path route it elsewhere
Jev only answers the question; your code decides what happens. Thresholds are yours to set per risk, higher for anything you can’t undo. TypeSafe’s guidance is to start conservative and tune on your own data.

The building blocks

Every question is one of three kinds

Jev’s makers call them Noul, Score and Choice. In plain words: a yes/no, a rating, or a pick from a list. You can ask several in one call, and each is answered on its own.

Noul

A yes/no, answered as a probability

“Is this answer supported by the source?”

0.94 0 · no 0.5 1 · yes one number between 0 and 1

Use it for: policy checks, evidence checks, “needs a human?” gates.

Score

A rating on a scale you define

“How frustrated is this customer?”

0.72 calm annoyed frustrated angry levels have an order

Use it for: severity, urgency, rubric grading, quality scores.

Choice

One pick from a list you supply

“Which team owns this ticket?”

billing technical 0.96 sales account no order, just the best match

Use it for: routing, categorizing, picking A vs. B.

10,000 outputs tonight’s answers to check every one Jev grades them fast, fractions of a cent confident unsure 9,500 settled pass or fail, no wait 500 to an LLM judge reasons and explains 460 settled there 40 still unclear 40 to a person the truly hard cases
Illustrative numbers. The slower, costlier steps only see what Jev couldn’t settle.

Why it matters

Cheap enough to check everything

Today most teams check a small sample of AI outputs, claims or tickets, because a large model reading every one costs too much and takes too long. Jev flips that. It grades all of them, settles the clear-cut cases on the spot, and hands only the uncertain ones up the chain.

That’s the pattern all three guides keep coming back to: Jev for the high-volume, closed questions; an LLM when someone needs the reasoning; a person when the decision really matters.

Honest caveat. Jev is in early access. Speed and cost figures come from vendor and partner tests, and TypeSafe doesn’t claim its probabilities are calibrated, so test thresholds on your own data before trusting them.

The three versions

Same brief, built in sequence

The three guides weren’t written in isolation. Each model worked from what came before, which is why some parts look alike and others don’t.

Claude Fable wrote the first draft: 100 one-line ideas across 17 industries. It then expanded every card with a “how it works” paragraph and a worked example.

Codex Astra kept the first draft’s look (its stylesheet is the same) but wrote a new set of 100: five per industry across 20 industries, each marked as fictional.

Grok took Codex Astra’s intro, industry list and first three cases word for word, then wrote 97 shorter cases of its own in a lighter, JavaScript-built page.

Claude Fable · draft 1 100 one-line ideas expanded styling reused Claude Fable · final + how it works, examples Codex Astra · r2 new 100, 20 industries intro + industry list + first 3 cases reused Grok 97 new, shorter cases
Highlighted boxes are the three versions on this site. Arrows show what each one carried forward.

See them whole

Browse all three side by side

Open the three full guides in columns and scroll each one. On a phone, switch between them with the tabs at the top.

Your turn

Got a use case? Share it

I like these examples, and I hope you do too. If you have more, share them, and let’s help each other out. Thank you!