assistant-ui

Active

Open Source React.js Library for AI Chat

Winter 2025Founded 20243 peopleSan Francisco, CA, USA

assistant-ui.com ↗LinkedIn ↗X ↗GitHub ↗See on the Idea Map B2B momentum

About

assistant-ui helps frontend developers add AI chat to their apps. Our product is used by several dozen companies, like LangChain, Stack AI, Browser Use, and Athena Intelligence. We're building an open source Typescript/React library and a backend as a service, with first class integrations into popular agent frameworks like LangGraph and Vercel AI SDK.

From their website

as of Jun 7, 2026assistant-ui.com ↗

Open SourceSubscription · Free tier available for the cloud backend with 200 MAU included; Pro plan at $50 per month with 500 MAU included and $0.10 per additional MAU; Enterprise/custom for large-scale deployments with custom MAU pricing and on-premises options. Forever free open-source option under MIT license for the libr

assistant-ui is an open-source React/TypeScript library that provides production-ready, ChatGPT-style UI components and state management for AI chat applications. It includes streaming, tools, persistence, and compatibility with various LLM backends, with a managed cloud backend option.

Provides drop-in, customizable UI components for AI chat, built with React and TypeScript. Features include streaming messages, multi-turn conversations, thread management, history persistence, and memory across sessions. It supports integrations with backends like Vercel AI SDK and LangChain, and can be deployed with either custom backends or the assistant-ui Cloud for persistent sessions and data replication. It emphasizes a ready-to-ship UI plus a scalable state management layer for AI chat experiences.

Who it’s for: AI-powered applications seeking a production-ready chat UI and state management, developers building chat copilots or agents, startups integrating AI chat into their apps, teams needing persistent chat sessions across refreshes.

Features

drop-in ChatGPT-style UI
streaming messages with interruptions/retries
multi-turn conversations
thread/history management
memory/persistence across sessions
high-performance, minimal bundle size
works with Vercel AI SDK, LangChain, or any LLM provider

mentions of pricing tiers, cloud backend offering, and enterprise/custom options indicate traction and commercial offering; references to adoption and integrations imply growth activity.

Founders · 1

Simon FarshidFounder

Simon is the Founder and CEO of assistant-ui. He previously co-founded READO, a book recommendation engine, and grew it to 140k MAUs. Simon started coding at age 12 and has won 8 hackathons in 5 countries.

LinkedIn ↗X ↗

Launch

Launched on Y Combinator · Feb 2025

View launch post ↗

The UX of ChatGPT in your own app, connected to your own AI agents.

assistant-ui is an open source TypeScript/React library for building in-app AI chat UIs. It provides pre-built, customizable components that connect to backends and AI SDKs, enabling human–agent collaboration, frontend tool calls, and chat history/analytics. It targets developers building AI-powered assistants within their own apps and announces its demos, installation commands, and collaboration features.