diff --git a/packages/better-fetch/tsup.config.ts b/packages/better-fetch/tsup.config.ts
index 1d6ae17..d05a302 100644
--- a/packages/better-fetch/tsup.config.ts
+++ b/packages/better-fetch/tsup.config.ts
@@ -1,11 +1,138 @@
 import { defineConfig } from "tsup";
 
+/**
+ * Fetch API type stubs prepended to built .d.ts files.
+ *
+ * The built .d.ts references Fetch API types (Response, Headers, RequestInit, etc.)
+ * as bare identifiers from lib.dom.d.ts. Consumers whose tsconfig does not include
+ * "DOM" in lib (e.g., backend projects with lib: ["ESNext"]) get TS2304 errors.
+ *
+ * These module-scoped declarations shadow DOM globals when DOM is present and provide
+ * the necessary types when it's absent. Since .d.ts files with export statements are
+ * modules, these declarations are file-scoped and do not pollute the global namespace.
+ */
+const FETCH_API_STUBS = `// -- Fetch API type stubs (self-contained for non-DOM environments) --
+
+// Simple string-literal union types
+type RequestCache = "default" | "force-cache" | "no-cache" | "no-store" | "only-if-cached" | "reload";
+type RequestCredentials = "include" | "omit" | "same-origin";
+type RequestMode = "cors" | "navigate" | "no-cors" | "same-origin";
+type RequestPriority = "auto" | "high" | "low";
+type RequestRedirect = "error" | "follow" | "manual";
+type ReferrerPolicy = "" | "no-referrer" | "no-referrer-when-downgrade" | "origin" | "origin-when-cross-origin" | "same-origin" | "strict-origin" | "strict-origin-when-cross-origin" | "unsafe-url";
+
+// Timer — opaque handle compatible with all runtimes
+type Timer = number | { ref(): void; unref(): void };
+
+// ReadableStream — minimal stub for body types
+interface ReadableStream<R = any> {
+  readonly locked: boolean;
+  getReader(): any;
+}
+
+// Fetch API interfaces — minimal subset covering usage in this package
+interface Headers {
+  append(name: string, value: string): void;
+  delete(name: string): void;
+  get(name: string): string | null;
+  has(name: string): boolean;
+  set(name: string, value: string): void;
+  forEach(callbackfn: (value: string, key: string, parent: Headers) => void): void;
+}
+type HeadersInit = [string, string][] | Record<string, string> | Headers;
+
+interface AbortSignal {
+  readonly aborted: boolean;
+  readonly reason: any;
+}
+
+interface AbortController {
+  readonly signal: AbortSignal;
+  abort(reason?: any): void;
+}
+
+interface Blob {
+  readonly size: number;
+  readonly type: string;
+  text(): Promise<string>;
+  arrayBuffer(): Promise<ArrayBuffer>;
+}
+declare var Blob: { new(blobParts?: any[], options?: any): Blob; prototype: Blob; };
+
+interface File extends Blob {
+  readonly name: string;
+  readonly lastModified: number;
+}
+declare var File: { new(fileBits: any[], fileName: string, options?: any): File; prototype: File; };
+
+interface URL {
+  href: string;
+  readonly origin: string;
+  protocol: string;
+  host: string;
+  hostname: string;
+  port: string;
+  pathname: string;
+  search: string;
+  hash: string;
+  toString(): string;
+}
+
+interface Response {
+  readonly ok: boolean;
+  readonly status: number;
+  readonly statusText: string;
+  readonly headers: Headers;
+  readonly body: ReadableStream<Uint8Array> | null;
+  readonly bodyUsed: boolean;
+  readonly url: string;
+  readonly redirected: boolean;
+  json(): Promise<any>;
+  text(): Promise<string>;
+  blob(): Promise<Blob>;
+  arrayBuffer(): Promise<ArrayBuffer>;
+  clone(): Response;
+}
+
+interface RequestInit {
+  method?: string;
+  headers?: HeadersInit;
+  body?: any;
+  mode?: RequestMode;
+  credentials?: RequestCredentials;
+  cache?: RequestCache;
+  redirect?: RequestRedirect;
+  referrer?: string;
+  referrerPolicy?: ReferrerPolicy;
+  integrity?: string;
+  keepalive?: boolean;
+  signal?: AbortSignal | null;
+  window?: null;
+  priority?: RequestPriority;
+  duplex?: string;
+}
+
+declare namespace globalThis {
+  interface Request {
+    readonly url: string;
+    readonly method: string;
+    readonly headers: Headers;
+    readonly body: ReadableStream<Uint8Array> | null;
+    clone(): globalThis.Request;
+  }
+}
+
+// -- End Fetch API type stubs --
+`;
+
 export default defineConfig({
 	entry: ["./src/index.ts"],
 	splitting: false,
 	sourcemap: true,
 	format: ["esm", "cjs"],
-	dts: true,
+	dts: {
+		banner: FETCH_API_STUBS,
+	},
 	clean: true,
 	external: ["zod"],
 });