# How to Vibe Code Your Own Lex (and Stop Paying for It)

> Collaborative documents, with powerful AI editing tools.

- Site: https://lex.page
- Category: SaaS
- Verdict: **Solid side project** (68/100 vibecodeable)
- Estimated effort: 2-3 weeks part-time

## Verdict

You can build a functional personal clone of Lex, but setting up bulletproof real-time CRDT synchronization alongside streaming AI inline commands will take deliberate engineering.

Replicating the clean writing canvas with TipTap and hooking up OpenAI/Anthropic APIs for the sidebar chat is straightforward boilerplate. The friction comes from coordinating real-time WebSocket state via Liveblocks and keeping inline autocompletion (`+++`) snappy while managing token streaming. A solo developer can build a robust personal-use clone in a few weekends, but matching the absolute polish of their production-grade collaborative engine requires ironing out edge cases in conflict resolution.

### What you can't replicate

- The 300,000-writer user base and community prompt library
- Enterprise negotiated data-privacy add-on terms directly with frontier model providers

## What it does

An AI-powered, minimalist collaborative word processor designed for long-form writing and refinement.

### Core features

- Minimalist rich-text markdown writing canvas
- Inline AI autocompletion triggered by +++
- Ask Lex sidebar chat for document refactoring and brainstorming
- Multi-model provider integration (OpenAI and Anthropic APIs)
- Context tagging and knowledge base document linking
- Real-time collaborative editing with live cursors
- Timeline-based version history and named checkpoints
- Developer API and Kit newsletter export integration

## The business

### Pricing

- Free: $0 — Basic document editing and collaboration with capped AI responses.
- Lex Pro: $18/mo — Full access to frontier models and advanced editing features.

### Funding

$2.72M raised.
- Seed
Investors: True Ventures

Founded 2022.
Team size: 4 to 10 employees.

## The hard parts

- Implementing a conflict-free replicated data type (CRDT) engine over WebSockets for concurrent multi-user editing without race conditions
- Managing token pruning, chunking, and multi-file RAG context injection for large documents without blowing past rate limits or latency thresholds
- Handling state synchronization between real-time editor mutations and streaming inline AI completion overlays

## How to vibe code Lex

### Prerequisites

- Node.js (free): Required runtime for the Next.js full-stack framework and package management.
- GitHub (free): Source code repository and deployment pipeline integration.
- Anthropic API Key (pay-as-you-go): Powers the Claude models used for Ask Lex chat and inline autocompletion.

### Recommended AI tools

- Claude Code: Agentic CLI tool to scaffold the entire Next.js structure, TipTap editor hooks, and database schemas rapidly.
- Cursor: Ideal for iterative UI styling of the minimalist markdown canvas and managing complex React component states.

### Stack

- Frontend: Next.js (App Router) with Tailwind CSS and TipTap Editor
- Backend: Next.js API Routes and Server Actions
- Database: Turso (SQLite at the edge)
- Auth: better-auth
- Payments: none
- Other: Liveblocks for real-time multiplayer co-editing and CRDT state, Vercel AI SDK for model streaming and inline prompt completions, Anthropic API / OpenAI API

### Hosting

- Vercel (Hosting the Next.js frontend, serverless API routes, and edge functions.): $0-20/mo

### Build guide

1. **Scaffold Project & Database** — Initialize a Next.js project with Tailwind CSS, configure Turso SQLite via Drizzle ORM, and set up better-auth.

```
Initialize a new Next.js 16 project using TypeScript, App Router, and Tailwind CSS v4. Set up Drizzle ORM configured with Turso (libSQL) as the database driver. Create database schemas for users, documents (id, title, content, userId, createdAt, updatedAt), document versions, and context tags. Implement better-auth for secure email/password and session handling. Ensure the project structure cleanly separates server actions, database queries, and client components.
```

2. **Build Minimalist Writing Canvas** — Integrate TipTap rich-text editor with markdown extensions and a distraction-free minimalist layout.

```
Create a distraction-free writing canvas component using TipTap editor with extensions for StarterKit, Typography, Placeholder, and TaskList. Style the editor with a clean, minimalist typography layout reminiscent of a high-end word processor (maximum content width, subtle borders, typewriter spacing). Implement auto-saving state indicators in the top bar that persist document changes to the backend database every 2 seconds after typing stops.
```

3. **Integrate Real-Time Collaboration** — Wire up Liveblocks to handle multi-user live cursors and Yjs CRDT document synchronization.

```
Integrate Liveblocks into the TipTap editor to enable multiplayer co-editing. Configure the Liveblocks Yjs provider to sync document content across connected clients in real time. Render remote user avatars and colored live cursors with usernames inside the editor canvas. Add a share document modal that generates unique collaborator links with permission toggles.
```

4. **Add Ask Lex Sidebar & AI Chat** — Implement a collapsible sidebar chat using Vercel AI SDK to query and edit document context.

```
Build an Ask Lex sidebar chat drawer using the Vercel AI SDK useChat hook. Allow users to select between Anthropic Claude and OpenAI GPT models from a dropdown selector. Implement context injection so the AI reads the active document contents and selected text blocks. Support standard actions like 'Brainstorm Titles', 'Find Weak Arguments', and custom prompt inputs that stream responses directly back into the chat or replace highlighted selections.
```

5. **Implement Inline Autocomplete Command (+++)** — Build an inline trigger handler that requests AI text continuation when typing three plus signs.

```
Add a custom TipTap extension or keyboard shortcut listener that detects when a user types '+++' inline. When triggered, capture the preceding paragraph context, show a subtle loading spinner badge in the editor, and call a streaming server action utilizing the Vercel AI SDK streamText endpoint. Seamlessly append the generated continuation text directly into the document stream at the cursor position.
```

6. **Version Control & Timeline Scrubbing** — Create a version checkpoint system allowing users to view and restore document history.

```
Build a version control subsystem that automatically records named checkpoints and periodic snapshots of document content into the database. Create a slide-over timeline history UI component that lists past saves with timestamps. Implement a restoration action that safely reverts the current document state to any selected historical checkpoint while creating a backup branch of the current edit.
```

### Cost vs paying

**Starting costs (one-time):**

- Custom domain (optional): $12/yr
- Total: ~$12 one-time

**Ongoing costs (monthly):**

- Vercel Hobby / Cloudflare Hosting: $0/mo
- Turso Database: $0/mo
- Anthropic & OpenAI API usage (personal scale): ~$5-15/mo
- Liveblocks (free tier up to 50 MAU): $0/mo
- Total: ~$5-15/mo

- Paying for the SaaS instead: $18/mo (Lex Pro)
- Build time: 35-50 hours
- AI tool credits: $20/mo (Claude Pro / Cursor Pro)
- Break-even: Build for learning and personal customization rather than cost savings.

## Sources

- [Lex Official Website](https://lex.page)
- [Tracxn Company Profile: Lex](https://tracxn.com)
- [GetLatka Company Metrics: Lex, Inc](https://getlatka.com)