Agent Elements

Production-ready React components for chat, tools, and AI workflows.

A shadcn-style registry of agent UI primitives — message lists, streaming markdown, tool cards (Bash, Edit, Search, Todo, Plan…), clarifying questions, and a composable input bar — built on React 19, Tailwind v4, and the Vercel AI SDK.

Live site · Docs · Discord · 21st.dev

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What's in the box

• AgentChat — drop-in chat shell that wires MessageList + InputBar, dispatches tool invocations to renderers, and handles the empty state.
• Tool cards — BashTool, EditTool (with diffs + approval), SearchTool, TodoTool, PlanTool, ToolGroup, SubagentTool, McpTool, ThinkingTool, GenericTool.
• Question tool — clarifying questions with single / multi / free-text answers.
• Composer pieces — InputBar, Suggestions, ModelPicker, ModeSelector, SendButton, AttachmentButton, FileAttachment.
• Streaming bits — Markdown (safe streaming), TextShimmer, SpiralLoader.

26 components total — see the full catalog at agent-elements.21st.dev/docs or the registry index at /r/index.json.

Install components

The registry is shadcn-compatible. Pull in agent-chat and it transitively installs everything it needs:

npx shadcn@latest add https://agent-elements.21st.dev/r/agent-chat.json

Files land under components/agent-elements/. Pick individual pieces the same way:

npx shadcn@latest add https://agent-elements.21st.dev/r/bash-tool.json
npx shadcn@latest add https://agent-elements.21st.dev/r/input-bar.json

Requirements: React 19, Tailwind v4, a shadcn-initialised project (npx shadcn@latest init).

Quick example

"use client";

import { AgentChat } from "@/components/agent-elements/agent-chat";
import { BashTool } from "@/components/agent-elements/tools/bash-tool";
import { EditTool } from "@/components/agent-elements/tools/edit-tool";
import { SearchTool } from "@/components/agent-elements/tools/search-tool";
import { useChat } from "@ai-sdk/react";

export default function Chat() {
  const { messages, status, sendMessage, stop } = useChat();

  return (
    <AgentChat
      messages={messages}
      status={status}
      onSend={({ content }) => sendMessage({ text: content })}
      onStop={stop}
      toolRenderers={{
        Bash: BashTool,
        Edit: EditTool,
        Write: EditTool,
        Search: SearchTool,
      }}
    />
  );
}

Skill for Claude Code & friends

A bundled skills.sh skill teaches AI assistants the component catalog, prop shapes, and composition rules so they stop hallucinating imports.

npx skills add 21st-dev/agent-elements

Source: skills/agent-elements/SKILL.md. More at docs/skills.

Local development

This repo is both the registry source and the documentation site (Next.js 16). To run it:

pnpm install
pnpm dev          # http://localhost:3000

Other scripts:

Script	What it does
pnpm dev	Next.js dev server
pnpm build	Rebuilds the registry, then builds the site (prebuild hook)
pnpm registry:build	Generates public/r/*.json from lib/agent-ui/
pnpm lint / pnpm format	ESLint / Prettier

Project structure

.
├── app/                   Next.js app — landing page, /docs, /api/agent
├── lib/agent-ui/          Component source (the library)
├── scripts/build-registry.mts   Compiles lib/agent-ui → public/r/*.json
├── public/r/              Generated shadcn registry (committed)
├── skills/agent-elements/ skills.sh bundle (SKILL.md + README)
└── agents/my-agent/       Example @21st-sdk/agent definition

The registry builder resolves intra-library imports, rewrites @/lib/agent-ui/* → @/components/agent-elements/*, and emits one JSON per component plus an index.

Part of the 21st.dev Agent SDK

Agent Elements is the UI layer of the 21st.dev Agent SDK. If you just want the components, everything above works on its own — plug them into any React app and wire them to your backend.

If you need a full agent (Claude Code or Codex running in a sandbox, with threads, streaming, tool approvals, and this UI out of the box), use the SDK directly. You get the same components, preconfigured, plus the runtime.

→ Explore the Agent SDK

Stack

Next.js 16 · React 19 · Tailwind v4 · Vercel AI SDK · shadcn · Base UI · Motion · Shiki · @21st-sdk/*

Links

• Site: agent-elements.21st.dev
• Registry index: agent-elements.21st.dev/r/index.json
• LLM-friendly docs: agent-elements.21st.dev/llms-full.txt
• Issues: github.com/21st-dev/agent-elements/issues
• Discord: discord.gg/Aq2B7bCp

License

MIT — built by 21st.dev.