remix.config.js

This file has a few build and development configuration options, but does not actually run on your server.

/** @type {import('@remix-run/dev').AppConfig} */
module.exports = {
  appDirectory: "app",
  assetsBuildDirectory: "public/build",
  future: {
    /* any enabled future flags */
  },
  ignoredRouteFiles: ["**/*.css"],
  publicPath: "/build/",
  routes(defineRoutes) {
    return defineRoutes((route) => {
      route("/somewhere/cool/*", "catchall.tsx");
    });
  },
  serverBuildPath: "build/index.js",
};

appDirectory

The path to the app directory, relative to remix.config.js. Defaults to "app".

// default
exports.appDirectory = "./app";

// custom
exports.appDirectory = "./elsewhere";

assetsBuildDirectory

The path to the browser build, relative to remix.config.js. Defaults to "public/build". Should be deployed to static hosting.

browserNodeBuiltinsPolyfill

The Node.js polyfills to include in the browser build. Polyfills are provided by JSPM and configured via esbuild-plugins-node-modules-polyfill.

/** @type {import('@remix-run/dev').AppConfig} */
module.exports = {
  browserNodeBuiltinsPolyfill: {
    modules: {
      buffer: true, // Provide a JSPM polyfill
      fs: "empty", // Provide an empty polyfill
    },
    globals: {
      Buffer: true,
    },
  },
};

When using this option and targeting non-Node.js server platforms, you may also want to configure Node.js polyfills for the server via serverNodeBuiltinsPolyfill.

cacheDirectory

The path to a directory Remix can use for caching things in development, relative to remix.config.js. Defaults to ".cache".

future

The future config lets you opt-into future breaking changes via Future Flags. The following future flags currently exist in Remix v2 and will become the default behavior in Remix v3:

v3_fetcherPersist: Change fetcher persistence/cleanup behavior in 2 ways (RFC):
- Fetchers are no longer removed on unmount, and remain exposed via useFetchers until they return to an idle state
- Fetchers that complete while still mounted no longer persist in useFetchers since you can access those fetchers via useFetcher
v3_relativeSplatPath: Fixes buggy relative path resolution in splat routes. Please see the React Router docs for more information.
v3_throwAbortReason: When a server-side request is aborted, Remix will throw the request.signal.reason instead of an error such as new Error("query() call aborted...")
unstable_singleFetch: Opt into Single Fetch behavior

ignoredRouteFiles

This is an array of globs (via minimatch) that Remix will match to files while reading your app/routes directory. If a file matches, it will be ignored rather than treated like a route module. This is useful for ignoring CSS/test files you wish to colocate.

publicPath

The URL prefix of the browser build with a trailing slash. Defaults to "/build/". This is the path the browser will use to find assets.

/** @type {import('@remix-run/dev').AppConfig} */
module.exports = {
  publicPath: "/assets/",
};

If you wish to serve static assets from a separate domain you may also specify an absolute path:

/** @type {import('@remix-run/dev').AppConfig} */
module.exports = {
  publicPath: "https://static.example.com/assets/",
};

postcss

Whether to process CSS using PostCSS if a PostCSS config file is present. Defaults to true.

/** @type {import('@remix-run/dev').AppConfig} */
module.exports = {
  postcss: false,
};

routes

A function for defining custom routes, in addition to those already defined using the filesystem convention in app/routes. Both sets of routes will be merged.

exports.routes = async (defineRoutes) => {
  // If you need to do async work, do it before calling `defineRoutes`, we use
  // the call stack of `route` inside to set nesting.

  return defineRoutes((route) => {
    // A common use for this is catchall routes.
    // - The first argument is the React Router path to match against
    // - The second is the relative filename of the route handler
    route("/some/path/*", "catchall.tsx");

    // if you want to nest routes, use the optional callback argument
    route("some/:path", "some/route/file.js", () => {
      // - path is relative to parent path
      // - filenames are still relative to the app directory
      route("relative/path", "some/other/file");
    });
  });
};

server

A server entrypoint, relative to the root directory that becomes your server's main module. If specified, Remix will compile this file along with your application into a single file to be deployed to your server. This file can use either a .js or .ts file extension.

serverBuildPath

The path to the server build file, relative to remix.config.js. This file should end in a .js extension and should be deployed to your server. Defaults to "build/index.js".

serverConditions

The order of conditions to use when resolving server dependencies' exports field in package.json.

serverDependenciesToBundle

A list of regex patterns that determines if a module is transpiled and included in the server bundle. This can be useful when consuming ESM only packages in a CJS build, or when consuming packages with CSS side effect imports.

For example, the unified ecosystem is all ESM-only. Let's also say we're using a @sindresorhus/slugify which is ESM-only as well. Here's how you would be able to consume those packages in a CJS app without having to use dynamic imports:

/** @type {import('@remix-run/dev').AppConfig} */
module.exports = {
  appDirectory: "app",
  assetsBuildDirectory: "public/build",
  publicPath: "/build/",
  serverBuildPath: "build/index.js",
  ignoredRouteFiles: ["**/*.css"],
  serverDependenciesToBundle: [
    /^rehype.*/,
    /^remark.*/,
    /^unified.*/,
    "@sindresorhus/slugify",
  ],
};

If you want to bundle all server dependencies, you can set serverDependenciesToBundle to "all".

serverMainFields

The order of main fields to use when resolving server dependencies. Defaults to ["main", "module"] when serverModuleFormat is set to "cjs". Defaults to ["module", "main"] when serverModuleFormat is set to "esm".

serverMinify

Whether to minify the server build in production or not. Defaults to false.

serverModuleFormat

The output format of the server build, which can either be "cjs" or "esm". Defaults to "esm".

serverNodeBuiltinsPolyfill

The Node.js polyfills to include in the server build when targeting non-Node.js server platforms. Polyfills are provided by JSPM and configured via esbuild-plugins-node-modules-polyfill.

/** @type {import('@remix-run/dev').AppConfig} */
module.exports = {
  serverNodeBuiltinsPolyfill: {
    modules: {
      buffer: true, // Provide a JSPM polyfill
      fs: "empty", // Provide an empty polyfill
    },
    globals: {
      Buffer: true,
    },
  },
};

When using this option, you may also want to configure Node.js polyfills for the browser via browserNodeBuiltinsPolyfill.

serverPlatform

The platform the server build is targeting, which can either be "neutral" or "node". Defaults to "node".

tailwind

Whether to support Tailwind functions and directives in CSS files if tailwindcss is installed. Defaults to true.

/** @type {import('@remix-run/dev').AppConfig} */
module.exports = {
  tailwind: false,
};

watchPaths

An array, string, or async function that defines custom directories, relative to the project root, to watch while running remix dev. These directories are in addition to appDirectory.

exports.watchPaths = async () => {
  return ["./some/path/*"];
};

// also valid
exports.watchPaths = ["./some/path/*"];

File Name Conventions

There are a few conventions that Remix uses you should be aware of.

Dilum Sanjaya made an awesome visualization of how routes in the file system map to the URL in your app that might help you understand these conventions.