diff --git a/src/lib/core.ts b/src/lib/core.ts
index 641322b..1c38482 100644
--- a/src/lib/core.ts
+++ b/src/lib/core.ts
@@ -87,10 +87,10 @@ export class Fintoc {
   whoami: WhoamiManager;
   v2: FintocV2;
 
-  constructor(apiKey: string, jwsPrivateKey?: string) {
+  constructor(apiKey: string, jwsPrivateKey?: string, options?: { userAgent?: string }) {
     this.#client = new Client({
       baseUrl: `${API_BASE_URL}`,
-      userAgent: `fintoc-node/${version}`,
+      userAgent: options?.userAgent || `fintoc-node/${version}`,
       apiKey,
       jwsPrivateKey,
     });
diff --git a/src/spec/core.spec.ts b/src/spec/core.spec.ts
index 71a8fb8..9624b20 100644
--- a/src/spec/core.spec.ts
+++ b/src/spec/core.spec.ts
@@ -9,3 +9,17 @@ test('"Fintoc" object creation', (t) => {
   t.assert(fintoc.links instanceof LinksManager);
   t.assert(fintoc.webhookEndpoints instanceof WebhookEndpointsManager);
 });
+
+test('"Fintoc" object creation with custom userAgent', (t) => {
+  const apiKey = 'super_secret_api_key';
+  const fintoc = new Fintoc(apiKey, undefined, { userAgent: 'fintoc-cli/0.1.0' });
+  t.assert(fintoc.links instanceof LinksManager);
+  t.assert(fintoc.webhookEndpoints instanceof WebhookEndpointsManager);
+  t.is((fintoc.links as any)._client.userAgent, 'fintoc-cli/0.1.0');
+});
+
+test('"Fintoc" object creation uses default userAgent when not provided', (t) => {
+  const apiKey = 'super_secret_api_key';
+  const fintoc = new Fintoc(apiKey);
+  t.true((fintoc.links as any)._client.userAgent.startsWith('fintoc-node/'));
+});