Index
An AI-native document editor — Cursor for writers.
MOTIVATION
Why build an AI document editor?
Software engineers have Cursor. Writers should have something just as powerful. Index (code-named Graphite) is an AI-native document editor that brings the same copilot-driven workflow that developers enjoy to anyone working with text — writers, researchers, students, and knowledge workers.
The idea came from noticing that while AI coding tools have become incredibly sophisticated, writing tools still treat AI as an afterthought — a sidebar chatbot bolted onto a text area. Index is built from the ground up around AI, with a copilot that understands the full context of your document.
FEATURES
What Index does
- Rich text editing powered by PlateJS with full formatting support — code blocks, math (KaTeX), markdown, lists, and more
- AI Copilot sidebar that can help draft, edit, summarize, and restructure your documents
- MCP integration with Model Context Protocol for extensible AI capabilities
- Exa web search built in, so the AI can pull in real-time information
- Cross-platform — a Next.js web app paired with an Expo React Native mobile companion
- Auth & storage via Supabase with document management and templates
ARCHITECTURE
How it's built
The web application is built with Next.js 16 and React 19, using PlateJS as the rich text editor engine. PlateJS provides a plugin-based architecture allowing features like autoformat, code blocks, markdown shortcuts, math rendering, and indentation to be composed together cleanly.
The AI layer uses the OpenAI SDK combined with the MCP SDK for structured tool use, and Exa for web search grounding. Authentication and data persistence are handled by Supabase.
The mobile companion is built with Expo and React Native, using local SQLite storage for offline-first document editing.