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      • server.cors

      • Type: boolean | import('cors').CorsOptions
      • Default:
      const defaultAllowedOrigins =
  /^https?:\/\/(?:(?:[^:]+\.)?localhost|127\.0\.0\.1|\[::1\])(?::\d+)?$/;

const defaultOptions = {
  // Default allowed:
  // - localhost
  // - 127.0.0.1
  // - [::1]
  origin: defaultAllowedOrigins,
};
      • Version: >= 1.1.11

      Configure CORS options for the dev server or preview server, based on the cors middleware.

      • object：Enable CORS with the specified options.
      • true：Enable CORS with default options (allow all origins, not recommended).
      • false：Disable CORS.
      Warning

      Using cors: true or cors.origin: '*' exposes your dev server to all origins and can compromise your source code security. We recommend using the origin option to specify an allowlist of trusted origins instead.

      Example

      • Enable CORS for a specific origin:
      rsbuild.config.ts
      export default {
  server: {
    cors: {
      // Configures the `Access-Control-Allow-Origin` CORS response header
      origin: 'https://example.com',
    },
  },
};
      • Keep the default origin config of Rsbuild and add additional origins:
      rsbuild.config.ts
      // `defaultAllowedOrigins` is the default origin value of Rsbuild
import { defaultAllowedOrigins } from '@rsbuild/core';

export default {
  server: {
    cors: {
      origin: [defaultAllowedOrigins, 'https://example.com'],
    },
  },
};
      • Only enable CORS for the dev server:
      rsbuild.config.ts
      const isDev = process.env.NODE_ENV === 'development';

export default {
  server: {
    cors: isDev ? { origin: 'https://example.com' } : false,
  },
};
      • Disable CORS:
      rsbuild.config.ts
      export default {
  server: {
    cors: false,
  },
};
      • Enable CORS for all origins (not recommended):
      rsbuild.config.ts
      export default {
  server: {
    // Equivalent to `{ origin: '*' }`
    cors: true,
  },
};

      Options

      The cors option can be an object, which is the same as the cors middleware options.

      The default configuration is the equivalent of:

      const defaultOptions = {
  origin: '*',
  methods: 'GET,HEAD,PUT,PATCH,POST,DELETE',
  preflightContinue: false,
  optionsSuccessStatus: 204,
};

      origin

      • Type:
      type StaticOrigin =
  | boolean
  | string
  | RegExp
  | Array<boolean | string | RegExp>;

type CustomOrigin = (
  requestOrigin: string | undefined,
  callback: (err: Error | null, origin?: StaticOrigin) => void,
) => void;

type Origin = StaticOrigin | CustomOrigin;

      The origin option is used to configure the Access-Control-Allow-Origin header:

      rsbuild.config.ts
      export default {
  server: {
    cors: {
      origin: 'https://example.com',
    },
  },
};

      Specify multiple allowed origins using an array:

      rsbuild.config.ts
      export default {
  server: {
    cors: {
      origin: [
        /^https?:\/\/(?:(?:[^:]+\.)?localhost|127\.0\.0\.1|\[::1\])(?::\d+)?$/,
        'https://example.com',
      ],
    },
  },
};

      Use a regular expression to allow all matching origins:

      rsbuild.config.ts
      export default {
  server: {
    cors: {
      origin: /\.example\.com$/,
    },
  },
};

      Setting origin to a function allows you to dynamically determine the allowed origin, the function receives two parameters:

      • origin：The origin of the incoming request, undefined if no origin is present.
      • callback：A function to set the allowed origin.
      rsbuild.config.ts
      export default {
  server: {
    cors: {
      origin: (origin, callback) => {
        // loadMyOrigins is an example call to load a list of origins
        loadMyOrigins((error, origins) => {
          callback(error, origins);
        });
      },
    },
  },
};