Architecture

How Stackseed is built

A Turborepo monorepo with four apps and thirteen shared packages. Everything is typed, everything is connected.

Data flows

How data moves through the system

Three primary flows handle authentication, background work, and billing.

Authentication

Client

Next.js App

BetterAuth

Supabase DB

Background jobs

API Routes

Trigger.dev

Resend

Billing

Polar Webhooks

Webhook Handler

Subscription Sync

Dependencies

Package dependency map

Each app imports only the packages it needs. No app depends on another app directly.

apps/webauth, db, payments, jobs, mail, ui, utils, i18n, analytics, types

apps/adminauth, db, ui, utils, i18n, analytics, types

apps/marketingui, utils, i18n, cms, analytics, types

apps/expoauth, db, ui, utils, types

Packages

All 13 packages

Every package lives in packages/ and is imported via the @workspace/* convention.

auth

BetterAuth integration with OAuth, email/password, 2FA, and organization support.

db

Supabase client wrappers for browser, server, and admin contexts. Typed queries.

payments

Polar billing integration — checkout, subscriptions, webhook handling.

jobs

Trigger.dev background tasks for emails, webhooks, and scheduled work.

mail

Resend email delivery with React Email templates for transactional mail.

ui

Shared shadcn/ui component library with Tailwind v4 styling.

utils

Constants, helper functions, and shared configuration values.

i18n

next-intl configuration with routing, middleware, and message loading.

analytics

Analytics provider and event tracking abstraction layer.

cms

Content management utilities for blog posts and changelog entries.

messaging

Notification and broadcast messaging system.

types

Shared TypeScript type definitions used across all apps.

typescript-config

Shared TypeScript configuration presets for Next.js and React libraries.

Communication

How apps communicate

Apps never import from each other directly. They communicate through shared packages and environment variables.

Shared packages

All business logic lives in packages/. Apps import via @workspace/auth, @workspace/db, etc. Changes to a package are available to every app that uses it.

Cross-app URLs via environment variables

NEXT_PUBLIC_APP_URL, NEXT_PUBLIC_ADMIN_URL, and NEXT_PUBLIC_MARKETING_URL let apps link to each other without hard-coded paths. Set them per environment.

Shared database

All apps connect to the same Supabase instance. Auth state, org data, and subscriptions are accessible from any app through @workspace/db.