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+---
+title: Use after() for Non-Blocking Operations
+impact: MEDIUM
+impactDescription: faster response times
+tags: server, async, logging, analytics, side-effects
+---
+
+## Use after() for Non-Blocking Operations
+
+Use Next.js's `after()` to schedule work that should execute after a response is sent. This prevents logging, analytics, and other side effects from blocking the response.
+
+**Incorrect (blocks response):**
+
+```tsx
+import { logUserAction } from "@/app/utils";
+
+export async function POST(request: Request) {
+  // Perform mutation
+  await updateDatabase(request);
+
+  // Logging blocks the response
+  const userAgent = request.headers.get("user-agent") || "unknown";
+  await logUserAction({ userAgent });
+
+  return new Response(JSON.stringify({ status: "success" }), {
+    status: 200,
+    headers: { "Content-Type": "application/json" },
+  });
+}
+```
+
+**Correct (non-blocking):**
+
+```tsx
+import { after } from "next/server";
+import { headers, cookies } from "next/headers";
+import { logUserAction } from "@/app/utils";
+
+export async function POST(request: Request) {
+  // Perform mutation
+  await updateDatabase(request);
+
+  // Log after response is sent
+  after(async () => {
+    const userAgent = (await headers()).get("user-agent") || "unknown";
+    const sessionCookie = (await cookies()).get("session-id")?.value || "anonymous";
+
+    logUserAction({ sessionCookie, userAgent });
+  });
+
+  return new Response(JSON.stringify({ status: "success" }), {
+    status: 200,
+    headers: { "Content-Type": "application/json" },
+  });
+}
+```
+
+The response is sent immediately while logging happens in the background.
+
+**Common use cases:**
+
+- Analytics tracking
+- Audit logging
+- Sending notifications
+- Cache invalidation
+- Cleanup tasks
+
+**Important notes:**
+
+- `after()` runs even if the response fails or redirects
+- Works in Server Actions, Route Handlers, and Server Components
+
+Reference: [https://nextjs.org/docs/app/api-reference/functions/after](https://nextjs.org/docs/app/api-reference/functions/after)