diff --git a/src/client.ts b/src/client.ts
index 41eba54..270d799 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -1,7 +1,10 @@
 import type { OpenSeaClientConfig } from "./types/index.js"
 
+declare const __VERSION__: string
+
 const DEFAULT_BASE_URL = "https://api.opensea.io"
 const DEFAULT_TIMEOUT_MS = 30_000
+const USER_AGENT = `opensea-cli/${__VERSION__}`
 
 export class OpenSeaClient {
   private apiKey: string
@@ -18,6 +21,14 @@ export class OpenSeaClient {
     this.verbose = config.verbose ?? false
   }
 
+  private get defaultHeaders(): Record<string, string> {
+    return {
+      Accept: "application/json",
+      "User-Agent": USER_AGENT,
+      "x-api-key": this.apiKey,
+    }
+  }
+
   async get<T>(path: string, params?: Record<string, unknown>): Promise<T> {
     const url = new URL(`${this.baseUrl}${path}`)
 
@@ -35,10 +46,7 @@ export class OpenSeaClient {
 
     const response = await fetch(url.toString(), {
       method: "GET",
-      headers: {
-        Accept: "application/json",
-        "x-api-key": this.apiKey,
-      },
+      headers: this.defaultHeaders,
       signal: AbortSignal.timeout(this.timeoutMs),
     })
 
@@ -69,10 +77,7 @@ export class OpenSeaClient {
       }
     }
 
-    const headers: Record<string, string> = {
-      Accept: "application/json",
-      "x-api-key": this.apiKey,
-    }
+    const headers: Record<string, string> = { ...this.defaultHeaders }
 
     if (body) {
       headers["Content-Type"] = "application/json"
diff --git a/test/client.test.ts b/test/client.test.ts
index d068dde..a4bf53b 100644
--- a/test/client.test.ts
+++ b/test/client.test.ts
@@ -39,10 +39,11 @@ describe("OpenSeaClient", () => {
         "https://api.opensea.io/api/v2/test",
         expect.objectContaining({
           method: "GET",
-          headers: {
+          headers: expect.objectContaining({
             Accept: "application/json",
+            "User-Agent": expect.stringMatching(/^opensea-cli\/\d+\.\d+\.\d+$/),
             "x-api-key": "test-key",
-          },
+          }),
         }),
       )
       expect(result).toEqual(mockResponse)
@@ -93,10 +94,11 @@ describe("OpenSeaClient", () => {
         "https://api.opensea.io/api/v2/refresh",
         expect.objectContaining({
           method: "POST",
-          headers: {
+          headers: expect.objectContaining({
             Accept: "application/json",
+            "User-Agent": expect.stringMatching(/^opensea-cli\/\d+\.\d+\.\d+$/),
             "x-api-key": "test-key",
-          },
+          }),
         }),
       )
       expect(result).toEqual(mockResponse)
@@ -111,11 +113,12 @@ describe("OpenSeaClient", () => {
         "https://api.opensea.io/api/v2/create",
         expect.objectContaining({
           method: "POST",
-          headers: {
+          headers: expect.objectContaining({
             Accept: "application/json",
             "Content-Type": "application/json",
+            "User-Agent": expect.stringMatching(/^opensea-cli\/\d+\.\d+\.\d+$/),
             "x-api-key": "test-key",
-          },
+          }),
           body: JSON.stringify({ name: "test" }),
         }),
       )
diff --git a/tsup.config.ts b/tsup.config.ts
index 2b0a0ea..aaf3f77 100644
--- a/tsup.config.ts
+++ b/tsup.config.ts
@@ -1,5 +1,10 @@
+import { readFileSync } from "node:fs"
 import { defineConfig } from "tsup"
 
+const pkg = JSON.parse(readFileSync("./package.json", "utf-8")) as {
+  version: string
+}
+
 export default defineConfig([
   {
     entry: { cli: "src/cli.ts" },
@@ -7,6 +12,9 @@ export default defineConfig([
     clean: true,
     sourcemap: true,
     target: "node18",
+    define: {
+      __VERSION__: JSON.stringify(pkg.version),
+    },
     banner: {
       js: "#!/usr/bin/env node",
     },
@@ -17,5 +25,8 @@ export default defineConfig([
     dts: true,
     sourcemap: true,
     target: "node18",
+    define: {
+      __VERSION__: JSON.stringify(pkg.version),
+    },
   },
 ])
diff --git a/vitest.config.ts b/vitest.config.ts
index 0de54ef..4bbf5f6 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -1,6 +1,14 @@
+import { readFileSync } from "node:fs"
 import { defineConfig } from "vitest/config"
 
+const pkg = JSON.parse(readFileSync("./package.json", "utf-8")) as {
+  version: string
+}
+
 export default defineConfig({
+  define: {
+    __VERSION__: JSON.stringify(pkg.version),
+  },
   test: {
     coverage: {
       provider: "v8",