Subchapter 3.10

Async API Routes

rules/async-api-routes.mdMarkdown1 KBView on GitHub

Prevent Waterfall Chains in API Routes

In API routes and Server Actions, start independent operations immediately, even if you don’t await them yet.

Incorrect (config waits for auth, data waits for both):

Async API Routes · Vercel React Best Practices · vercel-labs/agent-skills · Skills Docs

export async function GET(request: Request) {
  const session = await auth()
  const config = await fetchConfig()
  const data = await fetchData(session.user.id)
  return Response.json({ data, config })
}

export async function GET(request: Request) {
  const sessionPromise = auth()
  const configPromise = fetchConfig()
  const session = await sessionPromise
  const [config, data] = await Promise.all([
    configPromise,
    fetchData(session.user.id)
  ])
  return Response.json({ data, config })
}