Expo Project Structure

A starting skeleton for a new Expo app — one with no committed folder structure yet.

Apply only to new projects. If the app already has a layout, follow its existing conventions and leave files where they are — a default to start from, never a standard to enforce or migrate toward. When unsure whether a project is new, ask before moving anything.

The whole layout, assembled from the rules below:

├── assets/
├── scripts/
├── src/
│   ├── app/                       # Expo Router routes ONLY — every file is a route
│   │   ├── api/                   #   server API routes, grouped here
│   │   │   ├── user+api.ts
│   │   │   └── settings+api.ts
│   │   ├── _layout.tsx
│   │   ├── _layout.web.tsx         #   platform-specific layout
│   │   ├── index.tsx
│   │   └── settings.tsx
│   ├── components/                 # reusable UI: button, card, table…
│   │   ├── table/                  #   complex component → folder + index.tsx
│   │   │   ├── cell.tsx
│   │   │   └── index.tsx
│   │   ├── bar-chart.tsx
│   │   ├── bar-chart.web.tsx        #   platform-specific variant
│   │   └── button.tsx
│   ├── screens/                    # screen bodies that route files render
│   │   ├── home/
│   │   │   ├── card.tsx            #   used only by Home — not shared
│   │   │   └── index.tsx           #   rendered by src/app/index.tsx
│   │   └── settings.tsx
│   ├── server/                     # server-only helpers used by app/api
│   │   ├── auth.ts
│   │   └── db.ts
│   ├── utils/                      # standalone helpers + colocated tests
│   │   ├── format-date.ts
│   │   └── format-date.test.ts
│   ├── hooks/                      # reusable hooks: use-theme.ts…
│   ├── constants.ts
│   └── theme.ts
├── app.json
├── eas.json
└── package.json

src/ and src/app

Keep app code under src/ to separate it from config files. Expo Router supports both app/ and src/app/ out of the box — to switch, move the folder and restart the bundler. The default template aliases @/* to ./src/* in tsconfig.json.

src/app is routes-only: every file there becomes a route, so nothing else belongs in it. Everything below lives in sibling folders.

components/ — reusable UI

Generic, reused UI (button, card, table) with one named export each. Name files in kebab-case (bar-chart.tsx), matching the default create-expo-app template. When a component grows, give it its own folder with the root in index.tsx and colocate its private sub-components beside it — the import path (@/components/table) stays unchanged.

screens/ — screen bodies

Because app/ files must be routes, complex screen UI that isn't reused has no home there. Once a screen grows big enough to need breaking out to separate components, put it in screens/ and let each route just render its screen:

import { Home } from "@/screens/home";

export default function HomeScreen() {
  // route-specific concerns only — e.g. read url params here
  return <Home />;
}

Colocate a screen's private components inside its folder (screens/home/components/). A bonus: the same screen can render under multiple routes.

server/ + app/api/ — separate server code

Appending +api to a file in app/ makes it a server API route. Server code is different from frontend code — it runs in a Node-like server environment (deployed with EAS Hosting or on third-party services) and can read secret env vars (process.env.X, not just EXPO_PUBLIC_*). Keep it apart:

• Group all routes under app/api/ → /api/user, /api/settings. This colocates them and avoids collisions (e.g. a /user screen and a /user route).
• Put shared server-only helpers in src/server/.
• Consider ESLint rules that fence +api files and server/ off from frontend-only checks.

Platform-specific code

Small differences: use Platform.select / Platform.OS. For larger ones, split into platform files instead of inline if/else — bar-chart.tsx + bar-chart.web.tsx, imported extension-free (@/components/bar-chart); Metro picks the right file per target.

• Props must be identical across variants.
• A default file (no platform extension) is always required — make it a no-op if the component is single-platform.
• Supported extensions: .ios, .android, .native, .web.

Colocate styles and tests

• Styles: keep the StyleSheet.create({ ... }) object at the bottom of the component file rather than in a separate .styles file.
• Tests: put format-date.test.ts next to format-date.ts (preferred over a separate __tests__/ folder) so tested files are obvious at a glance.

AI and config files

Agent instructions live at the repo root — AGENTS.md / CLAUDE.md, with project skills under .claude/. Other config and assets stay outside src/: app.json / app.config.ts, eas.json, package.json, assets/, and scripts/.

Based on Expo app folder structure best practices by Kadi Kraman. For src/ precedence and alias mechanics, see the Expo docs.