Localise from the first byte.

Fields you need

Field	Use
country	Currency, legal banners (GDPR, CCPA), regional pricing
country_name	Human-readable "shipping to Germany"
region	US state for sales-tax routing; EU region for VAT
timezone	"Delivery at 3pm your time" instead of "3pm UTC"

Cloudflare Worker pattern (recommended)

At the CDN edge, look up the visitor IP once per session and cache the result in a signed cookie. Your origin never pays the RTT.

// Cloudflare Worker — geo-cookie
export default {
  async fetch(req, env) {
    const cookie = getCookie(req, 'ipa_geo');
    if (cookie) return fetch(req, { cf: { cookie } });

    const ip = req.headers.get('cf-connecting-ip');
    const r  = await fetch(`https://api.ip-atlas.io/json/${ip}`, {
      headers: { 'X-API-Key': env.IPATLAS_KEY }
    }).then(r => r.json());

    const res = await fetch(req);
    res.headers.append('Set-Cookie',
      `ipa_geo=${r.country}; Max-Age=86400; Path=/; Secure`);
    return res;
  }
};

Next.js middleware pattern

// middleware.ts
export async function middleware(req) {
  const ip = req.ip;
  const r  = await fetch(`https://api.ip-atlas.io/json/${ip}`, {
    headers: { 'X-API-Key': process.env.IPATLAS_KEY! }
  }).then(r => r.json());
  const res = NextResponse.next();
  res.cookies.set('country', r.country, { maxAge: 86400 });
  res.cookies.set('tz', r.timezone, { maxAge: 86400 });
  return res;
}

What NOT to do

• Don't hit the API on every render. One call per session is enough. Cache the country in a cookie or KV store.
• Don't geo-lock by browser language. Users in Berlin who set English as their browser language shouldn't see German pricing.
• Don't rely on IP for identity. Geo-IP is probabilistic; use it for UX, not KYC.