Fx0

Fx0 is an open-source web design agent that generates HTML pages from text descriptions.

Fx0 is an open-source design agent built to showcase the speed and durability of libfx. Users describe a page in a chat interface, and the agent generates the result as a single HTML file. Libfx runs the agent inside a Vercel Function, calling models and tools while streaming each step directly to the browser tab. Each chat operates as a libfx session saved step by step in a Workflow world, allowing a new function to pick up from the last step if the previous one dies mid-reply. Users can customize the system by editing instructions and tools in the source files.

Fx0 at a glance

Best for: Software engineer, Designer
Runs on: Web, open source
Pricing: Free prompts included
Released: October 2026
Category: AI coding tool
Website: fx0.vercel.dev

Key features

Generate HTML pages from text descriptions
Stream agent steps in real-time to the browser
Maintain durable chat sessions via Workflow worlds
Recover automatically from interrupted function replies
Customize agent instructions in TypeScript files
Define custom tools in TypeScript files

Use it for

Design web pages using text prompts
Build HTML files through an agent chat interface
Test libfx speed and durability

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