diff --git a/src/query.ts b/src/query.ts
index 407680a..d008608 100644
--- a/src/query.ts
+++ b/src/query.ts
@@ -69,6 +69,7 @@ async function query(
   const response = await fetch(config?.proxyEndpoint ?? API_URL, {
     headers: {
       'Content-Type': 'application/json; charset=utf-8',
+      ...config?.customHeader,
     },
     method: 'POST',
     body: buildRequestBody(params),
diff --git a/src/types.ts b/src/types.ts
index 766229e..343557e 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -37,4 +37,5 @@ export type ResponseParams = {
 
 export type Config = {
   proxyEndpoint?: string;
+  customHeader?: Record<string, string>;
 };