diff --git a/.changepacks/changepack_log_KSLv5lwwQVCRgMsInMFuh.json b/.changepacks/changepack_log_KSLv5lwwQVCRgMsInMFuh.json
new file mode 100644
index 0000000..831370f
--- /dev/null
+++ b/.changepacks/changepack_log_KSLv5lwwQVCRgMsInMFuh.json
@@ -0,0 +1 @@
+{"changes":{"packages/generator/package.json":"Patch"},"note":"Fix Formdata issue","date":"2026-02-18T18:18:07.532985400Z"}
\ No newline at end of file
diff --git a/examples/next/app/page.tsx b/examples/next/app/page.tsx
index 8aa1098..223e125 100644
--- a/examples/next/app/page.tsx
+++ b/examples/next/app/page.tsx
@@ -97,6 +97,10 @@ export default function Home() {
         tags: 'tag1,tag2',
       },
     })
+
+    api3.POST('/typed-form', {
+      body: new FormData(),
+    })
   }, [mutateAsync])
   return (
     <Box>
diff --git a/packages/generator/src/__tests__/__snapshots__/generate-interface.test.ts.snap b/packages/generator/src/__tests__/__snapshots__/generate-interface.test.ts.snap
index c017752..54ab29a 100644
--- a/packages/generator/src/__tests__/__snapshots__/generate-interface.test.ts.snap
+++ b/packages/generator/src/__tests__/__snapshots__/generate-interface.test.ts.snap
@@ -1834,13 +1834,13 @@ declare module "@devup-api/fetch" {
   interface DevupPostApiStruct {
     'openapi.json': {
       '/form': {
-        body: DevupObject<'request', 'openapi.json'>['SubscribeRequest'];
+        body: DevupObject<'request', 'openapi.json'>['SubscribeRequest'] | FormData;
         response?: {
           ok?: boolean;
         };
       };
       subscribe: {
-        body: DevupObject<'request', 'openapi.json'>['SubscribeRequest'];
+        body: DevupObject<'request', 'openapi.json'>['SubscribeRequest'] | FormData;
         response?: {
           ok?: boolean;
         };
@@ -1875,19 +1875,19 @@ declare module "@devup-api/fetch" {
   interface DevupPostApiStruct {
     'openapi.json': {
       '/form/contact': {
-        body?: {
-          name?: string;
-          email?: string;
-          message?: string;
-        };
+        body: {
+  name?: string;
+  email?: string;
+  message?: string;
+} | FormData;
         response?: {};
       };
       contact: {
-        body?: {
-          name?: string;
-          email?: string;
-          message?: string;
-        };
+        body: {
+  name?: string;
+  email?: string;
+  message?: string;
+} | FormData;
         response?: {};
       };
     }
@@ -1913,13 +1913,13 @@ declare module "@devup-api/fetch" {
   interface DevupPostApiStruct {
     'openapi.json': {
       '/typed-form': {
-        body: DevupObject<'request', 'openapi.json'>['CreateFileUploadRequest'];
+        body: DevupObject<'request', 'openapi.json'>['CreateFileUploadRequest'] | FormData;
         response?: {
           id?: string;
         };
       };
       createFileUpload: {
-        body: DevupObject<'request', 'openapi.json'>['CreateFileUploadRequest'];
+        body: DevupObject<'request', 'openapi.json'>['CreateFileUploadRequest'] | FormData;
         response?: {
           id?: string;
         };
@@ -1993,14 +1993,14 @@ declare module "@devup-api/fetch" {
         params: {
           id: string;
         };
-        body: DevupObject<'request', 'openapi.json'>['UpdateFileUploadRequest'];
+        body: DevupObject<'request', 'openapi.json'>['UpdateFileUploadRequest'] | FormData;
         response?: {};
       };
       updateFileUpload: {
         params: {
           id: string;
         };
-        body: DevupObject<'request', 'openapi.json'>['UpdateFileUploadRequest'];
+        body: DevupObject<'request', 'openapi.json'>['UpdateFileUploadRequest'] | FormData;
         response?: {};
       };
     }
@@ -2012,14 +2012,14 @@ declare module "@devup-api/fetch" {
         params: {
           id: string;
         };
-        body: DevupObject<'request', 'openapi.json'>['PatchFileUploadRequest'];
+        body: DevupObject<'request', 'openapi.json'>['PatchFileUploadRequest'] | FormData;
         response?: {};
       };
       patchFileUpload: {
         params: {
           id: string;
         };
-        body: DevupObject<'request', 'openapi.json'>['PatchFileUploadRequest'];
+        body: DevupObject<'request', 'openapi.json'>['PatchFileUploadRequest'] | FormData;
         response?: {};
       };
     }
@@ -2064,11 +2064,11 @@ declare module "@devup-api/fetch" {
         response?: {};
       };
       '/form': {
-        body: DevupObject<'request', 'openapi.json'>['SubscribeRequest'];
+        body: DevupObject<'request', 'openapi.json'>['SubscribeRequest'] | FormData;
         response?: {};
       };
       subscribe: {
-        body: DevupObject<'request', 'openapi.json'>['SubscribeRequest'];
+        body: DevupObject<'request', 'openapi.json'>['SubscribeRequest'] | FormData;
         response?: {};
       };
       '/form/upload': {
diff --git a/packages/generator/src/generate-interface.ts b/packages/generator/src/generate-interface.ts
index 2762acf..bfc0266 100644
--- a/packages/generator/src/generate-interface.ts
+++ b/packages/generator/src/generate-interface.ts
@@ -16,6 +16,7 @@ import {
   getRequestBodyContent,
   isErrorStatusCode,
   normalizeServerName,
+  resolveRef,
 } from './openapi-utils'
 import { wrapInterfaceKeyGuard } from './wrap-interface-key-guard'
 
@@ -117,6 +118,30 @@ function extractContentType(
   return extractInlineType(jsonContent.schema)
 }
 
+/**
+ * Check if a request body uses form or multipart content type.
+ */
+function isFormOrMultipartRequestBody(
+  requestBody: OpenAPIV3_1.RequestBodyObject | OpenAPIV3_1.ReferenceObject,
+  document: OpenAPIV3_1.Document,
+): boolean {
+  let content: OpenAPIV3_1.RequestBodyObject['content'] | undefined
+  if ('$ref' in requestBody) {
+    const resolved = resolveRef<OpenAPIV3_1.RequestBodyObject>(
+      requestBody.$ref,
+      document,
+    )
+    content = resolved?.content
+  } else {
+    content = requestBody.content
+  }
+  if (!content) return false
+  return (
+    content['multipart/form-data'] !== undefined ||
+    content['application/x-www-form-urlencoded'] !== undefined
+  )
+}
+
 // Generate interface for a single schema
 function generateSchemaInterface(
   schema: OpenAPIV3_1.Document,
@@ -346,6 +371,22 @@ function generateSchemaInterface(
           }
         }
         if (requestBodyType !== undefined) {
+          // For form/multipart endpoints, also allow FormData as body type
+          if (operation.requestBody) {
+            const isFormMultipart = isFormOrMultipartRequestBody(
+              operation.requestBody,
+              schema,
+            )
+            if (isFormMultipart) {
+              const bodyStr =
+                typeof requestBodyType === 'string'
+                  ? requestBodyType
+                  : formatTypeValue(requestBodyType)
+              if (!bodyStr.includes('FormData')) {
+                requestBodyType = `${bodyStr} | FormData`
+              }
+            }
+          }
           endpoint.body = requestBodyType
         }