Webhook vs API: Key Differences and When to Use Each

TL;DR

An API responds when your application makes a request. A webhook automatically sends your application data when a specific event occurs. Use APIs when you need to retrieve data or trigger an action on demand. Use webhooks when your system needs to react quickly without repeatedly polling for updates.

Most production applications use both: APIs establish or control a process, while webhooks report what happens afterward.

Webhooks and APIs Explained at a Glance

If you are deciding between a webhook and an API, the practical question is not which technology is better. It is who should initiate the communication.

With an API, your application starts the conversation:

1. Your application sends a request.
2. The remote service processes it.
3. The service returns a response.

With a webhook, the remote service starts the conversation after a predefined event:

1. An event occurs.
2. The service sends an HTTP request to your callback URL.
3. Your application accepts and processes the event.

For example, your application might use an API to start a payment, send an email, or create a real-time video room. It could then use webhooks to learn that the payment succeeded, the email bounced, or a participant left the room.

That distinction matters because it affects responsiveness, infrastructure cost, failure handling, and how much control your application has over timing.

Key Takeaways

• APIs are usually request-driven. Your application asks for data or requests an action and waits for a response.
• Webhooks are event-driven. A service sends an HTTP request to your application when a subscribed event occurs.
• Webhooks reduce polling. Your application does not need to check every few seconds for a change that may not have happened.
• APIs give the caller more control. Your application decides when to make the request and what information it needs.
• Webhooks require a reachable endpoint. You need a server that can receive, authenticate, acknowledge, and process incoming requests.
• Neither guarantees success by itself. API calls can time out, and webhook deliveries can be duplicated, delayed, or retried.
• They often work together. An API initiates or queries a workflow; a webhook reports later state changes.

Understanding the Webhook vs API Models

Webhooks and APIs both allow separate software systems to exchange information, but they solve different communication problems.

An API commonly follows a request-response model. Your application sends an HTTP request to an endpoint such as /orders/123, and the server returns data or an error.

A webhook is a user-configured HTTP callback. Instead of waiting for your application to ask whether something happened, the source service sends an event payload to a URL you provide.

The simplified “APIs pull, webhooks push” explanation is useful, but it is not a complete technical definition. An API is a broad interface through which software can expose data or functionality. A webhook is a specific event-notification pattern, usually implemented using HTTP. In that sense, a webhook endpoint may itself be part of an API surface.

What Is an API?

API stands for Application Programming Interface. It defines how one software component can interact with another.

In a web API, the contract usually specifies:

• Available endpoints
• Supported HTTP methods
• Required authentication
• Request parameters or body formats
• Response formats
• Status and error codes
• Rate limits

Suppose a dashboard needs the current status of a customer’s order. It can call an API:

GET /orders/123

The server might respond with the current state:

{
  "id": "123",
  "status": "shipped"
}

The caller chooses when to request the data. That makes APIs appropriate for loading pages, searching records, changing settings, creating resources, or checking a state at a specific moment.

However, if the application must detect a future change, it may need to poll the endpoint repeatedly. Frequent polling wastes requests when nothing has changed, while infrequent polling delays the update.

What Is a Webhook?

A webhook tells your application that an event has occurred without waiting for a new request from your application.

First, you register a callback URL and select the events you want. When one of those events occurs, the provider sends an HTTP request—usually a POST request—with an event payload.

For example:

{
  "event": "order.shipped",
  "eventId": "evt_891",
  "orderId": "123",
  "occurredAt": "2026-09-08T10:15:00Z"
}

Your endpoint validates the request, records or queues the event, and returns a successful HTTP status. Processing can then update a database, notify a customer, or trigger another workflow.

Webhooks are useful when an event may happen later or at an unpredictable time. Their tradeoff is added operational responsibility: the receiver must handle authentication, retries, duplicate events, out-of-order delivery, and temporary outages.

The Core Differences Between APIs and Webhooks

The following comparison addresses the central webhook vs API decision:

Decision factor	API	Webhook
Communication pattern	Request and response	Event-driven callback
Initiated by	The application needing data or an action	The system where the event occurs
Timing	When the client makes a request	When the subscribed event occurs
Typical data flow	Often described as pulling	Often described as pushing
Infrastructure needed	An API client	A publicly reachable callback endpoint
Best for	Queries, commands, setup, and on-demand actions	Notifications and asynchronous status changes
Freshness	Depends on request or polling frequency	Usually delivered shortly after the event
Failure handling	Client retries failed requests	Provider may retry failed deliveries
Common risk	Excessive polling or rate-limit pressure	Duplicate, forged, delayed, or unordered events

Choose an API when your application needs an immediate answer to a specific question or wants to initiate an action. Choose a webhook when it needs to respond after an event that the other system controls.

There are also cases where polling remains reasonable. If changes are rare but not time-sensitive, a scheduled API request may be easier to operate than a public webhook endpoint. Polling can also act as a reconciliation mechanism if missing an event would have serious consequences.

The strongest design is often hybrid:

1. Call an API to create or update a resource.
2. Store the returned resource ID.
3. Receive webhook events as its state changes.
4. Call the API again when you need the latest authoritative record.

Do not assume the webhook payload is always the final source of truth. Some providers intentionally send only an event type and resource ID, expecting your application to fetch the complete record through the API.

Stop Checking and Let the Event Call You

Imagine a coach waiting for a substitute player to finish warming up. One option is to call every minute and ask, “Are they ready now?” That resembles API polling. Most calls return the same answer, but they still consume attention and resources.

A webhook reverses the workflow: “Call me as soon as the player is ready.”

The coach can focus elsewhere until the relevant event occurs. In software, the callback might report that a file has finished processing, a payment has settled, or a participant has disconnected.

The analogy also exposes an important limitation. A callback can fail because the receiver is unavailable or the message is lost. Reliable webhook systems therefore retry deliveries, while reliable receivers acknowledge quickly and process events idempotently. For critical state, periodic API reconciliation can catch anything missed.

Practical Examples of APIs and Webhooks

Consider an application that sends transactional email.

The application uses an API when it wants to send a message. It provides the recipient, sender, subject, and content in a request. The service immediately returns whether that request was accepted.

Delivery happens asynchronously, so the initial API response cannot confirm that the recipient opened the message or that the receiving mail server rejected it. Webhooks can later report events such as:

• Delivered
• Bounced
• Opened
• Link clicked
• Spam complaint received

Inbound email follows a similar event-driven pattern. When a message arrives, the provider can send its parsed content to the application’s webhook instead of requiring the application to check for new messages repeatedly.

The same pattern appears in real-time audio and video applications. An API can authenticate a user, issue room credentials, or load a meeting record. Event-driven callbacks can report participant, recording, or moderation events. Inside the client, SDK event listeners also react to remote media becoming available, although these local listeners are not HTTP webhooks.

Getting Started with Webhooks Safely

Before adding a webhook, confirm that your workflow actually needs event-driven delivery. If users can tolerate a delayed update and the integration is small, occasional API polling may be simpler. If fast reaction or high polling volume matters, a webhook is usually the better fit.

Use this implementation sequence:

1. Choose specific events. Subscribe only to events your application can process.
2. Create an HTTPS endpoint. Give webhook traffic a dedicated route.
3. Verify authenticity. Validate the provider’s signature using the raw request body when required.
4. Acknowledge quickly. Return a successful response after validation and durable queuing rather than after a long business workflow.
5. Make processing idempotent. Store a unique event ID so retries do not create duplicate orders, messages, or notifications.
6. Expect retries and disorder. Events may arrive more than once or in a different order from when they occurred.
7. Monitor failures. Track invalid signatures, processing errors, retry volume, and queue delays.
8. Reconcile important state. Periodically use the API to verify critical records.

Keep webhook secrets outside source code, restrict payload size, and avoid trusting event fields before verification. The OWASP REST Security Cheat Sheet provides additional guidance for securing HTTP endpoints.

How to Build an App Like This with Tencent RTC

A custom calling, conference, or interactive live application demonstrates how APIs and event-driven callbacks work together. Tencent RTC Engine supplies the cross-platform real-time audio and video layer, including media transport, weak-network handling, monitoring, and media processing.

A practical architecture has four parts:

1. Client application: Uses trtc-sdk-v5 to enter a room, capture local media, publish it, and subscribe to remote media.
2. Application backend: Authenticates users and exposes an API that returns a room ID, user ID, SDK App ID, and short-lived UserSig.
3. Tencent RTC media service: Routes real-time audio and video between participants rather than sending media through your application server.
4. Event receiver and worker: Accepts configured server-side callbacks, verifies them, stores event IDs, and queues business actions.

Never generate UserSig in browser code because doing so would expose the signing secret. The client should request session configuration from your authenticated backend:

const session = await fetch('/api/rtc/session', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ roomId: 9001 })
}).then((response) => {
  if (!response.ok) throw new Error('Unable to create RTC session');
  return response.json();
});

The browser can then initialize Tencent RTC Engine. Starting local audio and video after room entry captures and publishes those tracks. The remote-media event triggers subscription and rendering when another participant publishes video:

import TRTC from 'trtc-sdk-v5';

const trtc = TRTC.create();

trtc.on(TRTC.EVENT.REMOTE_VIDEO_AVAILABLE, ({ userId, streamType }) => {
  trtc.startRemoteVideo({
    userId,
    streamType,
    view: `remote-${userId}`
  });
});

await trtc.enterRoom({
  sdkAppId: session.sdkAppId,
  userId: session.userId,
  userSig: session.userSig,
  roomId: session.roomId,
  scene: 'rtc'
});

await trtc.startLocalAudio();
await trtc.startLocalVideo({ view: 'local-video' });

Follow the Tencent RTC Engine overview and integration documentation when selecting the SDK and configuring the room lifecycle.

The ordered implementation path is:

1. Create the Tencent RTC application and keep its signing key on the backend.
2. Build an authenticated session API that issues time-limited client credentials.
3. Initialize trtc-sdk-v5 and enter the requested room.
4. Start local capture and publishing only after obtaining user permission.
5. Register event listeners before room entry so early remote-media events are not missed.
6. Subscribe to remote tracks and bind them to stable audio or video elements.
7. Add server-side callbacks only for backend workflows that need durable event notifications.
8. Make callback processing idempotent and use APIs or application records to reconcile critical state.

This division is deliberate: APIs handle user-controlled setup, Tencent RTC Engine handles latency-sensitive media, and event-driven callbacks handle asynchronous changes.

Frequently Asked Questions

Is a webhook an API?

A webhook is an HTTP callback pattern, while an API is a broader interface for software interaction. A webhook endpoint may technically be part of an API, but it reverses who initiates the request.

What is the main difference between a webhook and an API?

An API responds when your application requests data or an action. A webhook sends your application an event automatically when something happens.

Can an application use both APIs and webhooks?

Yes. A common design uses an API to start or query a workflow and webhooks to receive later status changes, with occasional API reconciliation for reliability.