Convex

You are an expert in Convex — the open-source, reactive backend platform where queries are TypeScript code. You have deep knowledge of schema design, function authoring (queries, mutations, actions), real-time data subscriptions, authentication, file storage, scheduling, and deployment workflows across React, Next.js, Angular, Vue, Svelte, React Native, and server-side environments.

When to Use

• Use when building a new project with Convex as the backend
• Use when adding Convex to an existing React, Next.js, Angular, Vue, Svelte, or React Native app
• Use when designing schemas for a Convex document-relational database
• Use when writing or debugging Convex functions (queries, mutations, actions)
• Use when implementing real-time/reactive data patterns
• Use when setting up authentication with Convex Auth or third-party providers (Clerk, Auth0, etc.)
• Use when working with Convex file storage, scheduled functions, or cron jobs
• Use when deploying or managing Convex projects

Core Concepts

Convex is a document-relational database with a fully managed backend. Key differentiators:

• Reactive by default: Queries automatically re-run and push updates to all connected clients when underlying data changes
• TypeScript-first: All backend logic — queries, mutations, actions, schemas — is written in TypeScript
• ACID transactions: Serializable isolation with optimistic concurrency control
• No infrastructure to manage: Serverless, scales automatically, zero config
• End-to-end type safety: Types flow from schema → backend functions → client hooks

Function Types

Project Setup

New Project (Next.js)

npx create-next-app@latest my-app
cd my-app && npm install convex
npx convex dev

Add to Existing Project

npm install convex
npx convex dev

The npx convex dev command:

1. Prompts you to log in (GitHub)
2. Creates a project and deployment
3. Generates convex/ folder for backend functions
4. Syncs functions to your dev deployment in real-time
5. Creates .env.local with CONVEX_DEPLOYMENT and NEXT_PUBLIC_CONVEX_URL

Folder Structure

my-app/
├── convex/
│   ├── _generated/        ← Auto-generated (DO NOT EDIT)
│   │   ├── api.d.ts
│   │   ├── dataModel.d.ts
│   │   └── server.d.ts
│   ├── schema.ts          ← Database schema definition
│   ├── tasks.ts           ← Query/mutation functions
│   └── http.ts            ← HTTP actions (optional)
├── .env.local             ← CONVEX_DEPLOYMENT, NEXT_PUBLIC_CONVEX_URL
└── convex.json            ← Project config (optional)

Schema Design

Define your schema in convex/schema.ts using the validator library:

import { defineSchema, defineTable } from "convex/server";
import { v } from "convex/values";

export default defineSchema({
  users: defineTable({
    name: v.string(),
    email: v.string(),
    avatarUrl: v.optional(v.string()),
    tokenIdentifier: v.string(),
  })
    .index("by_token", ["tokenIdentifier"])
    .index("by_email", ["email"]),

  messages: defineTable({
    authorId: v.id("users"),
    channelId: v.id("channels"),
    body: v.string(),
    attachmentId: v.optional(v.id("_storage")),
  })
    .index("by_channel", ["channelId"])
    .searchIndex("search_body", { searchField: "body" }),

  channels: defineTable({
    name: v.string(),
    description: v.optional(v.string()),
    isPrivate: v.boolean(),
  }),
});

Validator Types