Remix

import type { ActionFunctionArgs } from "@remix-run/node";
import { json } from "@remix-run/node";

async function isDisposable(email: string) {
  try {
    const r = await fetch(
      `https://api.disposableguard.com/v1/check?email=${encodeURIComponent(email)}`,
      { headers: { Authorization: `Bearer ${process.env.DG_KEY!}` } }
    );
    if (!r.ok) return false;
    const data = await r.json();
    return data.is_disposable === true;
  } catch {
    return false;
  }
}

export async function action({ request }: ActionFunctionArgs) {
  const formData = await request.formData();
  const email = formData.get("email");

  if (await isDisposable(String(email))) {
    return json({ error: "Please use a real email address." }, { status: 400 });
  }

  // ...signup logic
  return json({ ok: true });
}