expo-project-structure

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

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:

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.

Submitting Feedback

If you encounter errors, misleading or outdated information in this skill, report it so Expo can improve:

Only submit when you have something specific and actionable to report. Include as much relevant context as possible. If an AI agent repeatedly failed or the user had to take over an Expo task, load the expo-skill-feedback skill and follow its eval-candidate flow instead of reusing the command above.