LangChain UI Playground

Explore production-ready UI patterns for LangChain agent apps — across [React](https://react.dev/), [Vue](https://vuejs.org/), [Svelte](https://svelte.dev/), and [Angular](https://angular.dev/). Pick a framework, browse demos, and open in your editor. ## Framework Previews Every pattern is implemented across all four frontend frameworks. Choose a tab to browse demos. Render agent tool calls as rich cards — calculator, weather, search, email and more. Agent pauses and surfaces an approval card before taking a sensitive action. Server-driven dynamic UI — the agent emits structured component payloads rendered live. Collapsible chain-of-thought blocks that stream thinking tokens before the final answer. Agent returns typed structured data rendered with LaTeX math support. Branch conversation history and replay from any checkpoint using LangChain state. Visualize fan-out/fan-in parallel subgraph execution with merge indicators. Stream incremental tool progress using async iterators with live progress cards. Hierarchical activity cards for Deep Research-style multi-subagent orchestration. Agent builds and checks off a live todo list while executing a long-running task. IDE-like UI with file browser, code viewer, and diff panel backed by a sandbox environment. Timeline cards that visualize each LangGraph node as it executes in real time. Rich Markdown rendering with syntax-highlighted code blocks inside chat bubbles. Full chat interface with first-class branch navigation and history traversal. Visualize message queue state and throughput for multi-step agent pipelines. Stream output from multiple parallel subagents simultaneously with isolated windows. Render agent tool calls as rich cards — calculator, weather, search, email and more. Agent pauses and surfaces an approval card before taking a sensitive action. Server-driven dynamic UI — the agent emits structured component payloads rendered live. Collapsible chain-of-thought blocks that stream thinking tokens before the final answer. Agent returns typed structured data rendered with LaTeX math support. Branch conversation history and replay from any checkpoint using LangChain state. Visualize fan-out/fan-in parallel subgraph execution with merge indicators. Stream incremental tool progress using async iterators with live progress cards. Hierarchical activity cards for Deep Research-style multi-subagent orchestration. Agent builds and checks off a live todo list while executing a long-running task. IDE-like UI with file browser, code viewer, and diff panel backed by a sandbox environment. Timeline cards that visualize each LangGraph node as it executes in real time. Rich Markdown rendering with syntax-highlighted code blocks inside chat bubbles. Full chat interface with first-class branch navigation and history traversal. Visualize message queue state and throughput for multi-step agent pipelines. Stream output from multiple parallel subagents simultaneously with isolated windows. Render agent tool calls as rich cards — calculator, weather, search, email and more. Agent pauses and surfaces an approval card before taking a sensitive action. Server-driven dynamic UI — the agent emits structured component payloads rendered live. Collapsible chain-of-thought blocks that stream thinking tokens before the final answer. Agent returns typed structured data rendered with LaTeX math support. Branch conversation history and replay from any checkpoint using LangChain state. Visualize fan-out/fan-in parallel subgraph execution with merge indicators. Stream incremental tool progress using async iterators with live progress cards. Hierarchical activity cards for Deep Research-style multi-subagent orchestration. Agent builds and checks off a live todo list while executing a long-running task. IDE-like UI with file browser, code viewer, and diff panel backed by a sandbox environment. Timeline cards that visualize each LangGraph node as it executes in real time. Rich Markdown rendering with syntax-highlighted code blocks inside chat bubbles. Full chat interface with first-class branch navigation and history traversal. Visualize message queue state and throughput for multi-step agent pipelines. Stream output from multiple parallel subagents simultaneously with isolated windows. Render agent tool calls as rich cards — calculator, weather, search, email and more. Agent pauses and surfaces an approval card before taking a sensitive action. Server-driven dynamic UI — the agent emits structured component payloads rendered live. Collapsible chain-of-thought blocks that stream thinking tokens before the final answer. Agent returns typed structured data rendered with LaTeX math support. Branch conversation history and replay from any checkpoint using LangChain state. Visualize fan-out/fan-in parallel subgraph execution with merge indicators. Stream incremental tool progress using async iterators with live progress cards. Hierarchical activity cards for Deep Research-style multi-subagent orchestration. Agent builds and checks off a live todo list while executing a long-running task. IDE-like UI with file browser, code viewer, and diff panel backed by a sandbox environment. Timeline cards that visualize each LangGraph node as it executes in real time. Rich Markdown rendering with syntax-highlighted code blocks inside chat bubbles. Full chat interface with first-class branch navigation and history traversal. Visualize message queue state and throughput for multi-step agent pipelines. Stream output from multiple parallel subagents simultaneously with isolated windows. ## UI Framework Integrations Drop-in UI component libraries built to work with `@langchain/react` out of the box. Headless, composable React components for building AI chat UIs. Uses @[`useStream`] under the hood with full shadcn/ui compatibility. - Scroll-sticky conversation container - Streaming code blocks with syntax highlighting - Collapsible reasoning / thinking blocks - Tool call display with args & results - Shimmer loading states & suggestion chips A Claude-style assistant UI built with `@assistant-ui/react` primitives wired to LangChain via `useExternalStoreRuntime`. - Claude-style warm parchment theme - Chain-of-thought collapsible reasoning - Image attachment support - Copy / thumbs-up / thumbs-down action bar - Full dark mode support Generative UI chat where a LangChain agent emits arbitrary React components as part of the message stream — rendered live in the browser. - Agent-driven dynamic component rendering - Streaming message composition - Custom component registry - Live preview of generated interfaces