diff --git a/README.md b/README.md
index e621142..fe370fa 100644
--- a/README.md
+++ b/README.md
@@ -122,6 +122,40 @@ myBase.myMethod();
 myBase.myProperty;
 ```
 
+### TypeScript for a customized Base class
+
+If you write your `d.ts` files by hand instead of generating them from TypeScript source code, you can use the `ExtendBaseWith` Generic to create a class with custom defaults and plugins. It can even inherit from another customized class.
+
+```ts
+import { Base, ExtendBaseWith } from "../../index.js";
+
+import { myPlugin } from "./my-plugin.js";
+
+export const MyBase: ExtendBaseWith<
+  Base,
+  {
+    defaults: {
+      myPluginOption: string;
+    };
+    plugins: [typeof myPlugin];
+  }
+>;
+
+// support using the `MyBase` import to be used as a class instance type
+export type MyBase = typeof MyBase;
+```
+
+The last line is important in order to make `MyBase` behave like a class type, making the following code possible:
+
+```ts
+import { MyBase } from "./index.js";
+
+export async function testInstanceType(client: MyBase) {
+  // types set correctly on `client`
+  client.myPlugin({ myPluginOption: "foo" });
+}
+```
+
 ### Defaults
 
 TypeScript will not complain when chaining `.withDefaults()` calls endlessly: the static `.defaults` property will be set correctly. However, when instantiating from a class with 4+ chained `.withDefaults()` calls, then only the defaults from the first 3 calls are supported. See [#57](https://github.com/gr2m/javascript-plugin-architecture-with-typescript-definitions/pull/57) for details.
diff --git a/examples/rest-api-client-dts/README.md b/examples/rest-api-client-dts/README.md
new file mode 100644
index 0000000..13b6d0b
--- /dev/null
+++ b/examples/rest-api-client-dts/README.md
@@ -0,0 +1,20 @@
+# Custom class with defaults and plugins (TypeScript Declaration example)
+
+This example does not implement any code, it's meant as a reference for types only.
+
+Usage example:
+
+```js
+import { RestApiClient } from "javascript-plugin-architecture-with-typescript-definitions/examples/rest-api-client-dts";
+
+const client = new RestApiClient({
+  baseUrl: "https://api.github.com",
+  userAgent: "my-app/1.0.0",
+  headers: {
+    authorization: "token ghp_aB3...",
+  },
+});
+
+const { data } = await client.request("GET /user");
+console.log("You are logged in as %s", data.login);
+```
diff --git a/examples/rest-api-client-dts/index.d.ts b/examples/rest-api-client-dts/index.d.ts
new file mode 100644
index 0000000..d2c67d5
--- /dev/null
+++ b/examples/rest-api-client-dts/index.d.ts
@@ -0,0 +1,15 @@
+import { Base, ExtendBaseWith } from "../../index.js";
+
+import { requestPlugin } from "./request-plugin.js";
+
+export const RestApiClient: ExtendBaseWith<
+  Base,
+  {
+    defaults: {
+      userAgent: string;
+    };
+    plugins: [typeof requestPlugin];
+  }
+>;
+
+export type RestApiClient = typeof RestApiClient;
diff --git a/examples/rest-api-client-dts/index.js b/examples/rest-api-client-dts/index.js
new file mode 100644
index 0000000..8932b42
--- /dev/null
+++ b/examples/rest-api-client-dts/index.js
@@ -0,0 +1,5 @@
+import { Base } from "../../index.js";
+
+export const RestApiClient = Base.withPlugins([requestPlugin]).withDefaults({
+  userAgent: "rest-api-client/1.0.0",
+});
diff --git a/examples/rest-api-client-dts/index.test-d.ts b/examples/rest-api-client-dts/index.test-d.ts
new file mode 100644
index 0000000..8bffe51
--- /dev/null
+++ b/examples/rest-api-client-dts/index.test-d.ts
@@ -0,0 +1,54 @@
+import { expectType } from "tsd";
+
+import { RestApiClient } from "./index.js";
+
+// @ts-expect-error - An argument for 'options' was not provided
+let value: typeof RestApiClient = new RestApiClient();
+
+expectType<{ userAgent: string }>(value.defaults);
+
+expectType<{ userAgent: string }>(RestApiClient.defaults);
+
+// @ts-expect-error - Type '{}' is missing the following properties from type 'Options': myRequiredUserOption
+new RestApiClient({});
+
+new RestApiClient({
+  baseUrl: "https://api.github.com",
+  userAgent: "my-app/v1.0.0",
+});
+
+export async function test() {
+  const client = new RestApiClient({
+    baseUrl: "https://api.github.com",
+    headers: {
+      authorization: "token 123456789",
+    },
+  });
+
+  expectType<
+    Promise<{
+      status: number;
+      headers: Record<string, string>;
+      data?: Record<string, unknown>;
+    }>
+  >(client.request(""));
+
+  const getUserResponse = await client.request("GET /user");
+  expectType<{
+    status: number;
+    headers: Record<string, string>;
+    data?: Record<string, unknown>;
+  }>(getUserResponse);
+
+  client.request("GET /repos/{owner}/{repo}", {
+    owner: "gr2m",
+    repo: "javascript-plugin-architecture-with-typescript-definitions",
+  });
+}
+
+export async function testInstanceType(client: RestApiClient) {
+  client.request("GET /repos/{owner}/{repo}", {
+    owner: "gr2m",
+    repo: "javascript-plugin-architecture-with-typescript-definitions",
+  });
+}
diff --git a/examples/rest-api-client-dts/request-plugin.d.ts b/examples/rest-api-client-dts/request-plugin.d.ts
new file mode 100644
index 0000000..a7090c2
--- /dev/null
+++ b/examples/rest-api-client-dts/request-plugin.d.ts
@@ -0,0 +1,48 @@
+import { Base } from "../../index.js";
+
+declare module "../.." {
+  namespace Base {
+    interface Options {
+      /**
+       * Base URL for all http requests
+       */
+      baseUrl: string;
+
+      /**
+       * Set a custom user agent. Defaults to "rest-api-client/1.0.0"
+       */
+      userAgent?: string;
+
+      /**
+       * Optional http request headers that will be set on all requsets
+       */
+      headers?: {
+        authorization?: string;
+        accept?: string;
+        [key: string]: string | undefined;
+      };
+    }
+  }
+}
+
+interface Response {
+  status: number;
+  headers: Record<string, string>;
+  data?: Record<string, unknown>;
+}
+
+interface Parameters {
+  headers?: Record<string, string>;
+  [parameter: string]: unknown;
+}
+
+interface RequestInterface {
+  (route: string, parameters?: Parameters): Promise<Response>;
+}
+
+export declare function requestPlugin(
+  base: Base,
+  options: Base.Options
+): {
+  request: RequestInterface;
+};
diff --git a/examples/rest-api-client-dts/request-plugin.js b/examples/rest-api-client-dts/request-plugin.js
new file mode 100644
index 0000000..4f32f33
--- /dev/null
+++ b/examples/rest-api-client-dts/request-plugin.js
@@ -0,0 +1,12 @@
+/**
+ * This example does not implement any logic, it's just meant as
+ * a reference for its types
+ *
+ * @param {Base} base
+ * @param {Base.Options} options
+ */
+export function requestPlugin(base, options) {
+  return {
+    async request(route, parameters) {},
+  };
+}
diff --git a/index.d.ts b/index.d.ts
index 8594aab..68abbe6 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -51,10 +51,7 @@ type RequiredIfRemaining<PredefinedOptions, NowProvided> = NonOptionalKeys<
         NowProvided
     ];
 
-type ConstructorRequiringOptionsIfNeeded<
-  Class extends ClassWithPlugins,
-  PredefinedOptions
-> = {
+type ConstructorRequiringOptionsIfNeeded<Class, PredefinedOptions> = {
   defaults: PredefinedOptions;
 } & {
   new <NowProvided>(
@@ -156,4 +153,29 @@ export declare class Base<TOptions extends Base.Options = Base.Options> {
 
   constructor(options: TOptions);
 }
+
+type Extensions = {
+  defaults?: {};
+  plugins?: Plugin[];
+};
+
+type OrObject<T, Extender> = T extends Extender ? {} : T;
+
+type ApplyPlugins<Plugins extends Plugin[] | undefined> =
+  Plugins extends Plugin[]
+    ? UnionToIntersection<ReturnType<Plugins[number]>>
+    : {};
+
+export type ExtendBaseWith<
+  BaseClass extends Base,
+  BaseExtensions extends Extensions
+> = BaseClass &
+  ConstructorRequiringOptionsIfNeeded<
+    BaseClass & ApplyPlugins<BaseExtensions["plugins"]>,
+    OrObject<BaseClass["options"], unknown>
+  > &
+  ApplyPlugins<BaseExtensions["plugins"]> & {
+    defaults: OrObject<BaseExtensions["defaults"], undefined>;
+  };
+
 export {};
diff --git a/index.test-d.ts b/index.test-d.ts
index 316550c..5c6f504 100644
--- a/index.test-d.ts
+++ b/index.test-d.ts
@@ -1,5 +1,5 @@
 import { expectType } from "tsd";
-import { Base, Plugin } from "./index.js";
+import { Base, ExtendBaseWith, Plugin } from "./index.js";
 
 import { fooPlugin } from "./plugins/foo/index.js";
 import { barPlugin } from "./plugins/bar/index.js";
@@ -238,3 +238,48 @@ const baseWithManyChainedDefaultsAndPlugins =
 expectType<string>(baseWithManyChainedDefaultsAndPlugins.foo);
 expectType<string>(baseWithManyChainedDefaultsAndPlugins.bar);
 expectType<string>(baseWithManyChainedDefaultsAndPlugins.getFooOption());
+
+declare const RestApiClient: ExtendBaseWith<
+  Base,
+  {
+    defaults: {
+      defaultValue: string;
+    };
+    plugins: [
+      () => { pluginValueOne: number },
+      () => { pluginValueTwo: boolean }
+    ];
+  }
+>;
+
+expectType<string>(RestApiClient.defaults.defaultValue);
+
+// @ts-expect-error
+RestApiClient.defaults.unexpected;
+
+expectType<number>(RestApiClient.pluginValueOne);
+expectType<boolean>(RestApiClient.pluginValueTwo);
+
+// @ts-expect-error
+RestApiClient.unexpected;
+
+declare const MoreDefaultRestApiClient: ExtendBaseWith<
+  typeof RestApiClient,
+  {
+    defaults: {
+      anotherDefaultValue: number;
+    };
+  }
+>;
+
+expectType<string>(MoreDefaultRestApiClient.defaults.defaultValue);
+expectType<number>(MoreDefaultRestApiClient.defaults.anotherDefaultValue);
+
+declare const MorePluginRestApiClient: ExtendBaseWith<
+  typeof MoreDefaultRestApiClient,
+  {
+    plugins: [() => { morePluginValue: string[] }];
+  }
+>;
+
+expectType<string[]>(MorePluginRestApiClient.morePluginValue);
diff --git a/package.json b/package.json
index 19c48da..03e5b1a 100644
--- a/package.json
+++ b/package.json
@@ -16,7 +16,7 @@
     "test": "npm run -s test:code && npm run -s test:typescript && npm run -s test:coverage && npm run -s lint",
     "test:code": "c8 uvu . '^(examples/.*/)?test.js$'",
     "test:coverage": "c8 check-coverage",
-    "test:typescript": "tsd && tsd examples/*"
+    "test:typescript": "tsd && for d in examples/* ; do tsd $d; done"
   },
   "repository": "github:gr2m/javascript-plugin-architecture-with-typescript-definitions",
   "keywords": [