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Jev: 8 real use cases this fast, cheap model

John Lindquist created egghead.io, a developer education platform used by hundreds of thousands of working engineers. These days he’s building mega.dev, a hands-on program specifically for developers who want to do real work with AI agents, not just prototype them. *What you’ll learn:* 1. Why Jev is a decision engine, not a chatbot, and what that distinction actually changes about how you build 2. How John built a real-time voice to-do app that classifies and executes commands with no visible pause 3. The data deduplication pattern that merges messy records in milliseconds using confidence scores 4. Why Jev works best as a router, and how a single text input can navigate users deep into an app 5. What a chess match between Jev and a low-reasoning LLM reveals about speed, cost, and when to use which 6. The multi-step classification pattern John reaches for when one Jev pass isn’t enough 7. Where Jev falls short, and when you should still reach for a full generative model *Brought to you by:* Vanta—Automate compliance and simplify security: https://www.vanta.com/howiai *In this episode, we cover:* (00:00) John Lindquist returns for Jev week (04:32) What Jev actually outputs (06:15) Demo: real-time voice to-do app (08:17) How sequential Jev calls chain together (10:38) Demo: plain English to function name (grocery cart) (11:50) Demo: data deduplication and record merging (13:45) Confidence scores and multi-model validation (15:06) Demo: Jev as a multi-level app router (18:23) Architecting around Jev (19:35) Demo: Jev vs. traditional LLM at chess (speed and cost benchmarks) (24:29) DOM interactions as a decision set, not an infinite canvas (28:21) Demo: Wikipedia “path to philosophy” route mapper (30:28) Demo: multi-agent coordination and collision avoidance (33:36) Demo: real-time presentation coach (36:56) Quick recap (39:54) Lightning round and final thoughts *Tools referenced:* • Jev (TypeSafe AI decision model): https://typesafe.ai/blog/introducing-system-one-models-and-jev • Vercel AI Gateway: https://vercel.com/docs/ai-gateway • OpenRouter: https://openrouter.ai • Opus 5.5 (mentioned in context of iterative demo building): https://www.anthropic.com/claude-opus-5-5 *Where to find John Lindquist:* LinkedIn: linkedin.com/in/john-lindquist-84230766 X: https://x.com/johnlindquist Mega.dev: https://mega.dev/ Egghead.io: https://egghead.io/ *Where to find Claire Vo:* ChatPRD: https://www.chatprd.ai/ Website: https://clairevo.com/ LinkedIn: https://www.linkedin.com/in/clairevo/ X: https://x.com/clairevo _Production and marketing by https://penname.co/._ _For inquiries about sponsoring the podcast, email jordan@penname.co._

Claire VohostJohn Lindquistguest
Sep 30, 202646mWatch on YouTube ↗

At a glance

WHAT IT’S REALLY ABOUT

How Jev enables real-time, low-cost decision-driven product features

  1. Claire Vo and John Lindquist explain why Jev (a fast, cheap decision model) changes what product teams can build by turning natural language into structured choices, scores, and function calls instead of text.
  2. They demo real-time voice-driven interfaces (a to-do manager and a presentation coach) that rely on sequential Jev calls to validate streaming input, match entities, infer intent, and execute actions without pauses.
  3. They highlight high-ROI data operations—deduplication, record merging, clustering, and large-corpus discovery—made feasible by Jev’s low latency and very low token cost, especially when paired with confidence thresholds.
  4. They introduce Jev as an application/tool router that can sit above many smaller tools (or models) to route users to the right workflow, while noting that search-like experiences still require architecture choices such as clustering, caching, and batching.
  5. They contrast Jev with traditional LLMs using a chess benchmark and UI/DOM examples to show that decision models excel when the possible actions are constrained, while LLMs remain better for open-ended interpretation and creative analysis.

IDEAS WORTH REMEMBERING

5 ideas

Jev is best understood as a “decision/function layer,” not a chatbot.

Unlike chat-oriented LLMs (text-in/text-out), Jev is framed as unstructured input → structured decisions (function choice, labels, scores). This makes it especially useful for connecting natural language to APIs, tools, and deterministic product actions.

Speed + near-zero cost unlocks “previously not worth it” workflows at scale.

Multiple demos emphasize sub-second responses and extremely low costs (e.g., cents for many runs, ~4¢ per million input tokens discussed). That changes what’s economically feasible—like scanning huge JSON corpuses or running lots of comparisons that previously felt wasteful.

Real-time UX comes from chaining small, fast Jev calls—not one giant prompt.

The to-do voice demo chains several Jev passes: validate dictation quality, match text to an existing task, then match intent to an operation (remove/complete/priority). It can also detect when enough information has arrived mid-stream to safely execute a function call.

Use Jev to propose merges with confidence scores, then validate/explain with a second model.

For messy databases (duplicate contacts/companies/password entries), Jev can do pairwise matching and propose merges quickly, with confidence thresholds (e.g., only merge if ≥99%). A follow-up model can audit samples or generate human-readable rationales (“why these two are the same”).

Jev works well as an ultra-fast router for apps, tools, and even models.

They describe building Jev into a multi-level router: first pick the correct app/tool (e.g., “to-do app”), then pick the specific action inside that tool, enabling “go to X and do Y” flows. This extends to model routing (choosing which downstream model/tool to invoke).

WORDS WORTH SAVING

5 quotes

Fast and free are both amazing. Um, if you've ever been tired, uh, sending a basic request to an LLM and waiting around for a bit just to have it, like, call a function, this is now essentially instant.

— John Lindquist

This model, which is basically free and incredibly fast, allows you to do discovery over data in a way that feels like it's opening up my opportunities and allowing me to, like, look at things that I thought weren't high ROI before.

— Claire Vo

I think of LLMs being unstructured to unstructured—where you put text in, you get text out. And this one is similar. You put in unstructured sentences and data, but then you get structured data out.

— John Lindquist

Whenever you have constrained inputs like, uh, that are interacting with apps, it's, uh, Jev is a, a good thing to, to reach for.

— John Lindquist

Jev unlocks efficient inefficiency, which is like it is kind of like inefficient to map out all possible routes, rank them, double-check that they're not gonna collide.

— Claire Vo

Decision models vs. LLMs (structured outputs)Latency and cost economicsSequential/multi-pass classification pipelinesReal-time voice interfaces and streaming windowsDeduplication, record merging, confidence thresholdsTool/app/model routing (Jev as router)Constrained action spaces (DOM, games, chess)

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