diff --git a/src/app/api/compress-pdf/route.ts b/src/app/api/compress-pdf/route.ts
index e08edd5..0d9bf8d 100644
--- a/src/app/api/compress-pdf/route.ts
+++ b/src/app/api/compress-pdf/route.ts
@@ -7,12 +7,17 @@ const STIRLING_PDF_API_KEY =
 
 export async function POST(req: NextRequest) {
   try {
-    const formData = await req.formData();
-
+    // Stream body directly to Stirling — avoids FormData re-serialization
+    // failure on large files ("Failed to parse body as FormData")
     const res = await fetch(`${STIRLING_PDF_URL}/api/v1/misc/compress-pdf`, {
       method: "POST",
-      headers: { "X-API-KEY": STIRLING_PDF_API_KEY },
-      body: formData,
+      headers: {
+        "X-API-KEY": STIRLING_PDF_API_KEY,
+        "Content-Type": req.headers.get("content-type") || "",
+      },
+      body: req.body,
+      // @ts-expect-error duplex required for streaming request bodies in Node
+      duplex: "half",
     });
 
     if (!res.ok) {
diff --git a/src/app/api/compress-pdf/unlock/route.ts b/src/app/api/compress-pdf/unlock/route.ts
index 1a5b196..bcc6b6a 100644
--- a/src/app/api/compress-pdf/unlock/route.ts
+++ b/src/app/api/compress-pdf/unlock/route.ts
@@ -7,14 +7,19 @@ const STIRLING_PDF_API_KEY =
 
 export async function POST(req: NextRequest) {
   try {
-    const formData = await req.formData();
-
+    // Stream body directly to Stirling — avoids FormData re-serialization
+    // failure on large files ("Failed to parse body as FormData")
     const res = await fetch(
       `${STIRLING_PDF_URL}/api/v1/security/remove-password`,
       {
         method: "POST",
-        headers: { "X-API-KEY": STIRLING_PDF_API_KEY },
-        body: formData,
+        headers: {
+          "X-API-KEY": STIRLING_PDF_API_KEY,
+          "Content-Type": req.headers.get("content-type") || "",
+        },
+        body: req.body,
+        // @ts-expect-error duplex required for streaming request bodies in Node
+        duplex: "half",
       },
     );