assistant-ui YC Application

Winter 2025Active

assistant-ui went through Y Combinator in the Winter 2025 batch as a B2B company. Below: what the company does, who founded it, and its application to YC, reconstructed question by question in the real YC form.

YC batch: Winter 2025
Industry: B2BInfrastructure
Team size: 3
Status: Active
Launched: 2025

Founders

Simon FarshidFounder

What assistant-ui does

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.

assistant-ui's YC application, reconstructed

Y Combinator application

assistant-ui, Winter 2025 batch. The real form questions, answered from public data.

Founders2
Company7
Progress7
Idea4
Equity3
Curious2
Batch Preference1

Company

Company name

assistant-ui

Describe what your company does in 50 characters or less.

Open Source React.js Library for AI Chat

What is your company going to make? Please describe your product and what it does or will do.

We build assistant-ui, an open source TypeScript and React library that lets frontend developers easily add AI chat to their web apps. It includes a backend as a service and integrates natively with agent frameworks like LangGraph and the Vercel AI SDK. Our product removes the hassle of stitching different AI chat components together and scales to support teams shipping production AI assistants.

Where do you live now, and where would the company be based after YC?

We all live in San Francisco, CA, and plan to remain based here after YC.

Explain your decision regarding location.

San Francisco is where our team is already located and where our target users - frontend developers building AI chat - are concentrated. Staying here keeps us close to early customers and the developer ecosystem.

21 more answers in the full application

Founders, Progress, Idea, Equity, Curious, Batch Preference are in the full version. Create a free account to open it in YC Insights, next to every other YC batch.

See full application

Frequently Asked Questions

Is this the real assistant-ui YC application?

No. Y Combinator keeps submitted applications private. This is a reconstruction: the real YC form questions, answered from assistant-ui's public data (launch notes, founder backgrounds, product description). It shows how a company like assistant-ui would present itself to YC, not the text they submitted.