REST API, Webhooks and WebSockets: when to use each one

The three arrows

The three mechanisms differ by a single variable: who initiates the communication.

• REST API: you initiate. Your backend requests data and receives a response. Question → answer, and the connection dies.
• Webhooks: the platform initiates. When an event happens, your endpoint receives a POST with the data. You don't ask: you get pushed.
• WebSockets: you initiate once and the channel stays open. Both parties send at any time, without opening a connection per message.

Everything else — latency, complexity, scaling — is a consequence of that difference. Now, case by case.

REST: for querying, managing and reconciling

REST is the natural mechanism for everything that doesn't depend on something happening right now: attendance reports by date range, access audits, user and credential management, terminal status. It's easy to debug (one curl and done), fault tolerant (you retry and keep going) and needs nothing special in your infrastructure.

In API Connect, the REST API is also the source of truth: even if you consume real-time events, your payroll reconciliation and official reports must rely on the paginated REST reports — that way you don't depend on a live mechanism not having missed a moment.

Webhooks: for reacting to what happens

When your SaaS logic needs to act in the moment — notify the front desk, mark attendance live, trigger an alert for after-hours access — polling is a waste of API calls and unnecessary latency. The webhook flips the arrow: the platform POSTs the event to the URL you configure.

API Connect lets you set up the webhook URL (with an optional token to authenticate delivery) and sends a JSON POST for each event:

// Tu endpoint recibe el evento de la plataforma
app.post('/api-connect/eventos', (req, res) => {
  // Verifica el token de entrega antes de procesar
  if (req.headers.authorization !== `Bearer ${process.env.WEBHOOK_TOKEN}`) {
    return res.sendStatus(403);
  }

  const evento = req.body;
  // Ejemplo de payload de marcación:
  // { "Event Type": "Punch", "Event Description": "Access granted – door opened",
  //   "Serial number": "SN...", "Pin": "1234", "Date": "2026-09-14", "Time": "14:30:25" }

  console.log(evento["Pin"], evento["Date"], evento["Time"]);
  res.sendStatus(200); // responde rápido; procesa después
});

WebSockets: for live UI, not for your backend

Websockets shine in one very specific case: a user interface that needs high-frequency streaming — a live access dashboard updating across 50 screens at once. The persistent channel avoids the cost of opening a connection per message and lets you push to all subscribers at once.

But watch out for the classic trap: keeping one WebSocket connection per user is a serious operational responsibility (reconnects, load balancing, fan-out). In hardware integrations, the healthy pattern is: the webhook or stream reaches your backend, and your backend decides how to push it to browsers with its own realtime mechanism (one many SaaS already have).

The decision table

The recommended architecture in one sentence

Webhook for the urgent, REST for the truth, and your own realtime for the screens. With that combination, an access granted at 14:30:25 generates the alert in seconds (webhook), the end-of-month payroll reconciles against the official report (REST), and the supervisor's dashboard fills up live (your distribution channel).

Frequently asked questions