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Build payments that feel instant, global, inevitable.

LINK4TECH Kykeon is a fast, secure, developer-first payment processing API for E-commerce and POS. Pre-Auth, Capture, Void, Refund, Payout, DCC, Tokenization, Webhooks and more — unified in a single, beautifully-documented surface.

Version — OpenAPI 3.1

Endpoints — across all tags

Status

All systems operational

Heartbeat checks passing

Base URL

Productionkykeon.link4.tech Stagekykeons.link4.tech

Pre-Auth → Capture

Reserve funds, settle later. Clean two-phase flow with typed responses.

Void & Refund

Cancel authorisations or issue full/partial refunds with a single call.

DCC & Payout

Dynamic currency conversion and OCT transfers for global merchants.

PCI-grade security

Tokenization, encryption, and real-time heartbeat monitoring built-in.

Get started

Your first transaction in under a minute.

Provision a sandbox key, drop one of these snippets into your favourite terminal or runtime, and watch a pre-authorisation clear in real time.

curl -X POST 'https://kykeons.link4.tech/ecomapi/preauth/' \
  -H 'X-API-KEY: your_sandbox_key' \
  -H 'Content-Type: application/json' \
  -d '{
    "amount": "12.00",
    "currency": "EUR",
    "card_number": "4005529999000123",
    "expiry_date": "12/31",
    "cvv": "196",
    "cardholder_name": "John Doe",
    "transaction_reference": "order-00001"
  }'

const res = await fetch('https://kykeons.link4.tech/ecomapi/preauth/', {
  method: 'POST',
  headers: {
    'X-API-KEY': process.env.KYKEON_KEY,
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    amount: '12.00',
    currency: 'EUR',
    card_number: '4005529999000123',
    expiry_date: '12/31',
    cvv: '196',
    cardholder_name: 'John Doe',
    transaction_reference: 'order-00001'
  })
});
const data = await res.json();
console.log(data.transaction_id, data.status);

import os, requests

r = requests.post(
    'https://kykeons.link4.tech/ecomapi/preauth/',
    headers={'X-API-KEY': os.environ['KYKEON_KEY']},
    json={
        'amount': '12.00',
        'currency': 'EUR',
        'card_number': '4005529999000123',
        'expiry_date': '12/31',
        'cvv': '196',
        'cardholder_name': 'John Doe',
        'transaction_reference': 'order-00001',
    },
    timeout=15,
)
r.raise_for_status()
print(r.json()['transaction_id'], r.json()['status'])

payload := []byte(`{
  "amount":"12.00","currency":"EUR",
  "card_number":"4005529999000123",
  "expiry_date":"12/31","cvv":"196",
  "cardholder_name":"John Doe",
  "transaction_reference":"order-00001"
}`)
req, _ := http.NewRequest("POST",
  "https://kykeons.link4.tech/ecomapi/preauth/",
  bytes.NewBuffer(payload))
req.Header.Set("X-API-KEY", os.Getenv("KYKEON_KEY"))
req.Header.Set("Content-Type", "application/json")
resp, _ := http.DefaultClient.Do(req)
defer resp.Body.Close()
body, _ := io.ReadAll(resp.Body)
fmt.Println(string(body))

4005 5299 9900 0123 Public sandbox test card — approves on stage. Production keys require a formal processing agreement.