Bun & Elysia Backend

SuperImpress uses Bun as the JavaScript runtime and Elysia as the web framework for the backend.

Why Bun

• Performance: Significantly faster than Node.js for most workloads
• TypeScript Native: Runs TypeScript directly without compilation step
• All-in-One: Built-in bundler, test runner, and package manager
• Node.js Compatible: Works with most npm packages

Why Elysia

• Type Safety: End-to-end type inference from routes to handlers
• Performance: One of the fastest Bun web frameworks
• Plugin Ecosystem: First-party plugins for OpenAPI, auth, and more
• Developer Experience: Clean, expressive API design

Project Structure

backend/
├── src/
│   ├── index.ts          # App entry point
│   ├── auth.ts           # better-auth configuration
│   ├── db/
│   │   ├── index.ts      # Drizzle client
│   │   └── schema.ts     # Database schema
│   └── modules/
│       └── <domain>/     # Feature modules
└── drizzle/              # Migrations

TypeBox Validation

Elysia uses TypeBox for request/response validation with full type inference:

import { Elysia, t } from 'elysia';

const app = new Elysia()
  .post('/users', ({ body }) => {
    // body is typed as { name: string, email: string }
    return { id: 1, ...body };
  }, {
    body: t.Object({
      name: t.String(),
      email: t.String({ format: 'email' })
    })
  });

References

• Bun Documentation
• Elysia Documentation
• TypeBox