Is the Jev composer in a published release yet?

No, it is unreleased and needs a source build. The README fetched here describes the catalog, registry and Renderer and never mentions a composer, so you would be building against a repository tree rather than a versioned package.

Can the model invent components and props of its own?

No. You define the catalog with Zod schemas and output is constrained to it, which is the framework's central claim. A component or prop outside your catalog is absent from the schema, so the output cannot validate against it.

Can it type arbitrary text, or only fill in declared fields?

Only what your catalog declares. Props are typed, for example a Metric with label, value and a nullable format limited to currency, percent or number. Free-form prose requires a component you write yourself that accepts a string.

Does the schema guarantee mean the output is actually sensible?

It guarantees shape, not judgment. The README claims the JSON matches your schema every time and is streamed and rendered progressively. Which layout gets chosen and what values land in it are still yours to validate, and your code owns actions and side effects.

How do I install json-render?

Install @json-render/core plus a renderer package: @json-render/react and optionally @json-render/shadcn for 36 pre-built components, or vue, svelte, solid, react-native, remotion, react-pdf, react-email, ink or react-three-fiber.

What does a json-render catalog define?

Components with Zod prop schemas and descriptions plus actions, defined with defineCatalog; the registry maps those component names to renderers, and the Renderer takes a spec that references the catalog.

What license is json-render under?

Apache-2.0. It is a Vercel Labs product, and the Jev composer is unreleased: using it needs a source build and a Vercel AI Gateway key, while applications keep ownership of components, actions and side effects.

Jev directory

CommunityJev Repos & SDKs

JSON Render

Generative UI framework with an experimental Jev composer that selects components and layout from application-supplied candidates through Vercel AI Gateway, rendering catalog-constrained JSON specs.

See highlights Open github.com

Stars: 18.7k
Language: TypeScript
License: APACHE-2.0
Reading time: 2 min
Published by: Community
Author: vercel-labs
Last verified: Sep 2026

vercel-labs/json-render

Organization repository on GitHub

View on GitHub

The Generative UI framework

Forks: 995
Last pushed: Updated Oct 2026

Repo stats from the GitHub API, cached Oct 2026.Homepage

About this project

Generate dynamic, personalized UIs from prompts without sacrificing reliability. Predefined components and actions for safe, predictable output. json-render is a Generative UI framework: AI generates interfaces from natural language prompts, constrained to components you define. You set the guardrails, AI generates within them: Guardrailed - AI can only use components in your catalog. Predictable - JSON output matches your schema, every time. Fast - Stream and render progressively as the model responds.

Quoted from the project's README. Read the full README.

Tagscommunity typescript vercel gateway

Works forJev for Document processing

Used inJev for E-commerce & Retail

Highlights

Applications define a catalog of components and actions with Zod schemas, and AI output is constrained to that catalog.
Ships renderers for React, Vue, Svelte, Solid, React Native, Remotion, PDF, email, terminal and 3D, plus 36 shadcn/ui components.
The Jev composer is unreleased and needs a source build; application code owns components, actions and side effects.
The framework's core promise is JSON that matches your schema every time, streamed and rendered progressively.

Quickstart

import { defineCatalog } from "@json-render/core";
import { schema } from "@json-render/react/schema";
import { z } from "zod";

const catalog = defineCatalog(schema, {
  components: {
    Card: { props: z.object({ title: z.string() }), description: "A card container" },
  },
});

Watch out

Apache-2.0. The Jev API is unreleased and requires a source build and a Vercel AI Gateway key; applications keep ownership of components, actions and side effects.

Questions about this entry

Short answers drawn from the linked project or page.

Reactions & coverage

Posts, threads, and videos about this entry from around the web.

X: Jev lands on the Vercel AI Gateway

YouTube: Greg Isenberg and Ryan Vogel on the businesses Jev unlocks, and a path in through the Vercel AI Gateway.

X: Jev 1.14 is now on OpenRouter

X: Vercel ships the AI SDK provider for Jev

From the Jev guides

Original write-ups on what this entry is for.

Jev on the Gateways: Vercel, Workers AI, and OpenRouter

Oct 12, 2026

The request shape barely changes across surfaces; the surrounding contract does. When to call the API directly and when a gateway, a Worker binding, or a router entry earns its extra hop.

Jev Tools & CLIs#gateway#vercel#cloudflare

Read article

The Open Reimplementations: Local Models That Speak System One

Sep 22, 2026

Closed weights have not stopped the ecosystem from rebuilding the shape in the open. API-compatible servers, retrained heads on small models, and inference-time tricks that skip generation entirely.

Jev Repos & SDKs#open-models#research#local