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

> All gas, no breakages

- Site: https://convex.dev
- Category: Backend-as-a-Service (BaaS)
- Verdict: **Don't bother** (12/100 vibecodeable)
- Estimated effort: 6+ months of full-time systems programming (for a toy clone)

## Verdict

Build a simple single-tenant reactive CRUD wrapper instead, but keep paying for Convex if you need its distributed reactive engine.

Replicating Convex as a solo developer is a fool's errand because it requires building a custom database storage engine with write-ahead logs, distributed consensus transactions, and an automatic dependency-tracking reactive execution engine. While you can build a weekend prototype that polls a Postgres database or broadcasts basic WebSockets, replicating Convex's core engineering feat—transparent, zero-glue reactive query invalidation at scale—would take years of systems programming.

### What you can't replicate

- Ex-Dropbox distributed systems architecture and custom database engine
- Engineered automatic dependency-tracking reactive query cache
- Enterprise-grade SOC 2 Type II compliance and HIPAA business associate agreements
- Extensive ecosystem of verified production components and 1.2M weekly npm community momentum

## What it does

The reactive backend platform that replaces traditional databases, serverless functions, caching layers, and manual real-time websocket management with end-to-end type safety.

### Core features

- Reactive query execution engine with automatic dependency tracking
- Real-time websocket synchronization and state diff patching
- ACID transactions over distributed state with write-ahead logs
- TypeScript server functions (queries, mutations, actions)
- Sandboxed modular Convex Components (workpools, workflows, agents)
- Vector and text search capabilities
- Built-in file storage with S3-compatible backend

## The business

### Pricing

- Free & Starter: $0/mo — For personal projects and prototypes
- Professional: $25/dev/mo — For startups moving from prototype to production
- Business & Enterprise: $2,500/mo min — For teams scaling rapidly

### Funding

$29M raised.
- Series A ($26M, 2022)
- Growth Round ($24M, Nov 2025)
Investors: Andreessen Horowitz (a16z), Spark Capital, Neo Ventures, Alumni Ventures, Nat Friedman, Adam D'Angelo, Drew Houston

Founded 2021.
Team size: 36-50+.

## The hard parts

- Building a transactional reactive query caching and invalidation engine that pushes updates instantly when underlying table rows change
- Managing high-concurrency websocket state synchronization with differential patching across thousands of active clients
- Implementing custom ACID transactional execution semantics on top of a storage log engine
- Sandboxing modular TypeScript background workflows with durable retries, backoff, and checkpoints

## How to vibe code Convex

### Prerequisites

- Node.js (free): Required for running the TypeScript backend runtime and CLI tooling.
- GitHub (free): Version control and repository hosting.

### Recommended AI tools

- Claude Code: Best-in-class multi-file agentic coding tool for scaffolding complex TypeScript systems.

### Stack

- Frontend: Next.js
- Backend: Node.js / Express with custom WebSocket server
- Database: Neon
- Auth: better-auth
- Payments: Stripe
- Other: TypeScript, Docker

### Hosting

- Fly.io (Hosting the custom WebSocket sync server and backend runtime containers): $5/mo
- Neon (Serverless Postgres database storage for the personal subset clone): $0/mo

### Build guide

1. **Project Scaffolding & Database Schema** — Initialize the Next.js project with a TypeScript backend structure connected to a Neon Postgres database.

```
Initialize a new Next.js 16 project with TypeScript and Tailwind CSS v4. Set up a Drizzle ORM configuration connected to a Neon Postgres database endpoint via environment variables. Create a base schema file defining a generic 'documents' table with an id, collection name, JSONB data payload, and timestamps. Ensure strict type safety across database queries.
```

2. **Authentication Integration** — Configure better-auth for secure user session management.

```
Install and configure better-auth in the Next.js application using the Neon Postgres database as the persistent store. Implement email/password and GitHub OAuth sign-in flows. Create protected API routes and client-side session hooks to secure backend operations.
```

3. **WebSocket Sync Server** — Build a standalone Node.js WebSocket server to handle persistent client connections and state broadcasting.

```
Build a standalone Node.js WebSocket server using 'ws' and TypeScript, deployable on Fly.io. Implement client connection management, authentication token verification on handshake, and room-based channel subscriptions so clients can listen for mutations on specific database collections.
```

4. **Basic Reactive Mutation Loop** — Implement server-side mutations that update the database and broadcast change notifications to connected websocket clients.

```
Implement server-side mutation handlers in the backend. When a client executes a write mutation (insert, update, delete) on a collection, persist the change to Neon Postgres and immediately broadcast a change notification payload over active WebSockets to all subscribed clients in that collection room.
```

5. **Client-Side Reactive Hooks** — Develop React hooks on the frontend that automatically sync state with the WebSocket backend server.

```
Create a custom React hook 'useQuery' that fetches initial data via HTTP and subscribes to the WebSocket server for real-time updates. Ensure incoming websocket patch messages seamlessly update local React state without requiring manual page reloads or polling.
```

### Cost vs paying

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

- AI Coding Assistant (Claude Pro): $20
- Total: $20 one-time

**Ongoing costs (monthly):**

- Fly.io WebSocket Server: $5/mo
- Neon Postgres DB: $0/mo
- Total: $5/mo

- Paying for the SaaS instead: $25/dev/mo
- Build time: 120 hours
- AI tool credits: $20
- Break-even: Never (clone lacks core reactive distributed engine)

## Sources

- [Convex Official Website](https://convex.dev)
- [Convex Pricing Page](https://convex.dev/pricing)
- [Convex About Us Page](https://convex.dev/about)
- [Convex Enterprise Page](https://convex.dev/enterprise)
- [TechCrunch: Convex Raises $24M to Reinvent Backends](https://vertexaisearch.cloud.google.com/grounding-api-redirect/AUZIYQGKso8BmPdT85i19SwWtrTeU5OQN0_Wt1Mhy2RYrLZxlzORH9kUWJWjkskI5ib2SusU2LRrdx_Zt9YRKGEMKFqY8YzRmsMwS9Ikxl2ostgSeGJs8RWixlc0NOF9lmotPmA=)