One call.
Everything after is ours.

import { ePayX } from "@epayx/node";

const epx = new ePayX(process.env.EPX_KEY);

const { url } = await epx.checkout.create({
  product:    "prod_pro_yearly",
  customer:   { email: "[email protected]" },
  successUrl: "https://app.you.com/welcome",
});

// redirect the customer to `url`

from epayx import Client

epx = Client(api_key=os.environ["EPX_KEY"])

session = epx.checkout.create(
    product="prod_pro_yearly",
    customer_email="[email protected]",
    success_url="https://app.you.com/welcome",
)

# redirect the customer to session.url

curl https://api.epayx.com/v1/checkout \
  -u "$EPX_KEY:" \
  -d product=prod_pro_yearly \
  -d "customer[email][email protected]" \
  -d success_url=https://app.you.com/welcome

# → { "id": "cs_…", "url": "https://pay.epayx.com/cs_…" }