Folder Structure

The following is the folder structure of a newly scaffolded T3 App, with all options selected.

Further down, the description of each folder indicates its purpose and if it is only included with selected libraries.

.
├─ prisma
│  └─ schema.prisma
├─ public
│  └─ favicon.ico
├─ src
│  ├─ env
│  │  ├─ client.mjs
│  │  ├─ schema.mjs
│  │  └─ server.mjs
│  ├─ pages
│  │  ├─ api
│  │  │  ├─ auth
│  │  │  │  └─ [...nextauth].ts
│  │  │  ├─ trpc
│  │  │  │  └─ [trpc].ts
│  │  │  ├─ examples.ts
│  │  │  └─ restricted.ts
│  │  ├─ _app.tsx
│  │  └─ index.tsx
│  ├─ styles
│  │  └─ globals.css
│  ├─ types
│  │  └─ next-auth.d.ts
│  ├─ utils
│  │  └─ trpc.ts
│  ├─ server
│  │  ├─ common
│  │  │  └─ get-server-auth-session.ts
│  │  ├─ db
│  │  │  └─ client.ts
│  │  └─ trpc
│  │     ├─ router
│  │     │  ├─ _app.ts
│  │     │  ├─ auth.ts
│  │     │  └─ example.ts
│  │     ├─ context.ts
│  │     └─ trpc.ts
├─ .env
├─ .env.example
├─ .eslintrc.json
├─ next-env.d.ts
├─ next.config.mjs
├─ postcss.config.cjs
├─ prettier.config.cjs
├─ tailwind.config.cjs
└─ tsconfig.json

prisma

The prisma folder contains the schema.prisma file which is used to configure the database connection and the database schema. It is also the location to store migration files and/or seed scripts, if used. See Prisma usage for more information.

_{(With Prisma)}

public

The public folder contains static assets that are served by the web server. The favicon.ico file is an example of a static asset.

src/env

Used for environment variable validation and type definitions - see Environment Variables.

src/pages

The pages folder contains all the pages of the Next.js application. The index.tsx file at the root directory of /pages is the homepage of the application. The _app.tsx file is used to wrap the application with providers. See Next.js documentation↗ for more information.

src/pages/api

The api folder contains all the API routes of the Next.js application. The examples.ts file (with Prisma) contains an example of a route that uses the Next.js API route↗ feature along with Prisma. The restricted.ts file (with Next-Auth) contains an example of a route that uses the Next.js API route↗ feature and is protected by NextAuth.js↗.

_{(With NextAuth.js, tRPC or tRPC + Prisma)}

src/pages/api/auth/[...nextauth].ts

The [...nextauth].ts file is the NextAuth.js authentication slug route. It is used to handle authentication requests. See NextAuth.js usage for more information on NextAuth.js, and Next.js Dynamic Routes Docs↗ for info on catch-all/slug routes.

_{(with NextAuth.js)}

src/pages/api/trpc/[trpc].ts

The [trpc].ts file is the tRPC API entrypoint. It is used to handle tRPC requests. See tRPC usage for more information on this file, and Next.js Dynamic Routes Docs↗ for info on catch-all/slug routes.

_{(with tRPC)}

src/server

The server folder is used to clearly separate server-side code from client-side code.

_{(with tRPC and/or Prisma)}

src/server/common

The common folder contains commonly re-used server-side code.

_{(with NextAuth.js + tRPC)}

src/server/common/get-server-auth-session.ts

The get-server-auth-session.ts file is used to get the NextAuth.js session on the server-side. See NextAuth.js usage for more information.

_{(with NextAuth.js + tRPC)}

src/server/db/client.ts

The client.ts file is used to instantiate the Prisma client at global scope. See Prisma usage for more information.

_{(with Prisma)}

src/server/trpc

The trpc folder contains the tRPC server-side code.

_{(with tRPC)}

src/server/trpc/context.ts

The context.ts file is used to create the context used in tRPC requests. See tRPC usage for more information.

_{(with tRPC)}

src/server/trpc/trpc.ts

The trpc.ts file is used to export procedure helpers. See tRPC usage for more information.

_{(with tRPC)}

src/server/trpc/router

The router folder contains the tRPC routers.

_{(with tRPC)}

src/server/trpc/router/_app.ts

The _app.ts file is used to merge tRPC routers and export them as a single router, as well as the type definitions. See tRPC usage for more information.

_{(with tRPC)}

src/server/trpc/router/auth.ts

The auth.ts file is an example tRPC router utilizing the protectedProcedure helper to demonstrate how to protect a tRPC route with NextAuth.js.

_{(with NextAuth.js + tRPC)}

src/server/trpc/router/example.ts

The example.ts file is an example tRPC router utilizing the publicProcedure helper to demonstrate how to create a public tRPC route.

_{(with tRPC)}

src/styles

The styles folder contains the global styles of the application.

_{(with Tailwind CSS)}

src/types

The types folder is used to store reused types or type declarations.

_{(with NextAuth.js)}

src/types/next-auth.d.ts

The next-auth.d.ts file is used to extend the NextAuth default session type to include the user ID. See NextAuth.js usage for more information.

_{(with NextAuth.js)}

src/utils

The utils folder is used to store commonly re-used utility functions.

_{(with tRPC)}

src/utils/trpc.ts

The trpc.ts file is the front-end entrypoint to tRPC. See tRPC usage for more information.

_{(with tRPC)}

.env

The .env file is used to store environment variables. See Environment Variables for more information. This file should not be commited to git history.

.env.example

The .env.example file shows example environment variables based on the chosen libraries. This file should be commited to git history.

.eslintrc.json

The .eslintrc.json file is used to configure ESLint. See ESLint Docs↗ for more information.

next-env.d.ts

The next-env.d.ts file ensures Next.js types are picked up by the TypeScript compiler. You should not remove it or edit it as it can change at any time. See Next.js Docs↗ for more information.

next.config.mjs

The next.config.mjs file is used to configure Next.js. See Next.js Docs↗ for more information. Note: The .mjs extension is used to allow for ESM imports.

postcss.config.cjs

The postcss.config.cjs file is used for Tailwind PostCSS usage. See Tailwind PostCSS Docs↗ for more information.

_{(with Tailwind CSS)}

prettier.config.cjs

The prettier.config.cjs file is used to configure Prettier to include the prettier-plugin-tailwindcss for formatting Tailwind CSS classes. See the Tailwind CSS blog post↗ for more information.

_{(with Tailwind CSS)}

tsconfig.json

The tsconfig.json file is used to configure TypeScript. Some non-defaults, such as strict mode, have been enabled to ensure the best usage of TypeScript for create-t3-app and its libraries. See TypeScript Docs↗ or TypeScript Usage for more information.