Node.js

mkdir kyc-example && cd kyc-example
npm init -y
npm install express
export KAYWHYSEE_API_KEY="kyc_live_..."

const BASE_URL = "https://www.kaywhysee.com/api/v1";

async function call(method, path, body) {
  const response = await fetch(BASE_URL + path, {
    method,
    headers: {
      Authorization: `Bearer ${process.env.KAYWHYSEE_API_KEY}`,
      "Content-Type": "application/json",
    },
    body: body ? JSON.stringify(body) : undefined,
  });
  const data = await response.json();
  if (!response.ok) {
    const error = new Error(data.error?.message ?? `HTTP ${response.status}`);
    error.code = data.error?.code;
    error.status = response.status;
    throw error;
  }
  return data;
}

export const createSession = (reference, redirectUrl) =>
  call("POST", "/sessions", { reference, redirect_url: redirectUrl });

export const getSession = (id) => call("GET", `/sessions/${encodeURIComponent(id)}`);

export const cancelSession = (id) => call("POST", `/sessions/${encodeURIComponent(id)}/cancel`);

import express from "express";
import { createSession, getSession } from "./kaywhysee.js";

const app = express();
const sessions = new Map(); // your database, in real life: user id -> session id

// Your own sign-in decides who this is.
const currentUserId = (req) => "user_1042";

app.post("/verify", async (req, res) => {
  const userId = currentUserId(req);
  const session = await createSession(userId, "http://localhost:3000/verified");
  sessions.set(userId, session.id);
  res.redirect(303, session.start_url);
});

app.get("/verified", async (req, res) => {
  // Arriving here proves nothing: always ask the API.
  const session = await getSession(sessions.get(currentUserId(req)));
  if (session.outcome === "clear") return res.send("You're verified.");
  if (session.outcome === "rejected") return res.send("We couldn't verify you.");
  res.send(`Thanks! We're checking your details (status: ${session.status}).`);
});

app.get("/", (req, res) => 
  res.send('<form method="post" action="/verify"><button>Verify my identity</button></form>'),
);

app.listen(3000, () => console.log("http://localhost:3000"));

node server.js