Modern marketing and analytics stacks rely on dozens of tools that need to communicate with each other. CRMs, payment systems, websites, analytics tools, and advertising platforms all generate valuable events. The challenge is moving this data between systems quickly and reliably.
One of the most efficient ways to enable this communication is through webhooks.
Webhooks allow applications to automatically send data to another system when something important happens. Instead of repeatedly checking for updates, the system pushes information in real time.
In this article, we will explain:
- What webhooks are
- What a webhook server does
- How webhook communication works
- Common use cases for webhooks
- How webhooks can improve server-side tracking and conversion attribution
What is a webhook?
A webhook is a mechanism that allows one application to notify another application when a specific event occurs.
Rather than waiting for another system to request information, the application immediately sends an HTTP request to a predefined URL once the event happens.
A webhook request usually includes several components:
Endpoint URL
The destination address where the webhook request will be sent.
Payload
The event data that is being transmitted. Most webhooks use JSON, though XML is sometimes used as well.
Headers
Additional information describing how the request should be interpreted, such as content type or authentication data.
HTTP method
Most webhooks use the POST method because it allows sending structured event data.
Because webhooks deliver data automatically when an event occurs, they are ideal for real-time integrations.
For example, a webhook might be triggered when:
- a customer completes a purchase
- a new lead is added to a CRM
- a payment is processed
- a subscription renews
- a support ticket is created
Instead of waiting for updates, the receiving system is instantly notified.
What is a webhook server?
A webhook server is the system responsible for receiving and processing webhook requests.
It listens for incoming HTTP requests at a specific endpoint. When an event occurs in another system, that system sends a webhook request to the server.
Once the webhook server receives the request, it processes the payload and performs predefined actions.
Think of it as an event listener.
For example:
- A user completes a purchase in an online store
- The store sends a webhook request
- The webhook server receives the event
- The server processes the order data
- Additional actions are triggered
These actions could include updating internal systems, notifying teams, or forwarding the data to analytics platforms.
Why webhook servers are useful
Webhook servers make it possible to connect systems without complex integrations.
Some of the key benefits include:
Real-time communication
Webhooks deliver information as soon as an event occurs. This allows systems to react immediately instead of waiting for scheduled updates.
Reduced system load
Without webhooks, systems often rely on polling, which means repeatedly checking another service for changes. Polling consumes resources and creates unnecessary network traffic.
Webhooks remove this need by sending updates only when something changes.
Workflow automation
Webhooks are commonly used to trigger automated processes. For example, when a purchase occurs, a webhook can automatically update inventory, notify the logistics team, and record the sale in analytics tools.
Flexible integrations
Developers can build custom workflows that react to events from external services, making webhooks an important tool for extending application functionality.
How webhooks work
Although webhooks sound technical, the process behind them is quite straightforward.
Step 1: Configure the webhook
First, you define which system will send webhook notifications and which system will receive them.
You then register a URL where the webhook request should be delivered. This URL points to the webhook server.
You also choose which events should trigger the webhook.
For example:
- order created
- user registered
- payment completed
Step 2: An event occurs
When the selected event happens, the source application prepares a webhook request containing information about the event.
For instance, when an order is placed, the webhook payload might include:
- order ID
- order value
- customer details
- timestamp
Step 3: The request is sent
The application sends an HTTP request to the webhook endpoint.
The payload typically contains structured data describing the event.
Step 4: The webhook server receives the event
The webhook server listens for incoming requests and captures the event data once the request arrives.
At this stage, the server can validate the request and extract the relevant information.
Step 5: The server triggers actions
After processing the payload, the server can trigger various actions such as:
- updating databases
- notifying internal teams
- triggering automation workflows
- sending event data to analytics or advertising platforms
The webhook server may also return a response confirming that the event was successfully received.
Common use cases for webhooks
Webhooks are widely used across modern software ecosystems.
Below are some common examples.
Continuous integration and deployment
Development platforms like GitHub can send webhooks whenever code is pushed to a repository. This can automatically trigger build pipelines or deployment processes.
Payment notifications
Payment providers send webhooks when transactions are completed, failed, or refunded. This allows businesses to update order statuses instantly.
CRM automation
When a lead is created or updated in a CRM, webhooks can synchronize that data with marketing tools, analytics platforms, or internal databases.
Messaging and alerts
Communication platforms often support webhooks to send automated alerts to services like Slack when important events occur.
IoT systems
Devices and sensors can send webhook notifications when specific conditions are met, such as temperature thresholds or device status changes.
Webhooks in server-side tracking
Webhooks are particularly useful when working with server-side tracking setups.
Many important events do not happen directly on the website. Instead, they occur in external systems such as:
- CRMs
- payment processors
- backend databases
- customer support platforms
Webhooks allow these systems to send event data directly to a server-side Google Tag Manager container.
This enables teams to track events that would otherwise be difficult or impossible to capture using client-side tracking.
Examples include:
- offline purchases
- subscription renewals
- CRM lead updates
- phone order confirmations
Once the webhook reaches the server container, the event can be forwarded to advertising platforms, analytics tools, or internal reporting systems.
Example: tracking phone orders with webhooks
Consider a situation where a user clicks on your online advertisement and visits your website.
Instead of purchasing immediately, the user calls your sales team and completes the order over the phone.
From an analytics perspective, this conversion may be difficult to attribute to the original ad click.
Webhooks solve this problem.
When the phone order is created in the CRM, the CRM can send a webhook containing the order details to your server-side tracking endpoint.
Your server container can then forward this data to advertising platforms as an offline conversion.
If the platform can match the order to the original click, the conversion will be attributed to the correct campaign.
This helps marketers measure campaign performance more accurately.
Webhooks vs APIs
Both APIs and webhooks allow systems to exchange information, but they follow different communication models.
API communication
With APIs, the client sends a request asking the server for information. The server then responds with the requested data.
This means the client must actively check for updates.
Webhook communication
Webhooks follow an event-based approach.
Instead of asking for updates, the receiving system simply waits for notifications. When an event occurs, the sending system pushes the data automatically.
The key difference
The main distinction lies in who initiates the interaction.
With APIs, the client initiates the request.
With webhooks, the server sends the notification when an event happens.
In many systems, APIs and webhooks work together: APIs provide access to data, while webhooks notify systems about changes.
Setting up webhooks for event tracking
Although the exact setup process varies across platforms, the overall workflow is usually similar.
Identify the event source
Determine where the event occurs. This could be a CRM, CMS, payment system, or backend application.
Configure webhook delivery
Set up the system to send webhook requests to your server endpoint whenever the selected event occurs.
Build a webhook listener
Create a webhook listener capable of receiving and processing incoming requests.
Forward event data
After the webhook is received, extract the relevant data and send it to your analytics or marketing platforms.
This approach enables real-time event tracking while avoiding many of the limitations of browser-based tracking.
Conclusion
Webhooks are a simple yet powerful way to enable real-time communication between applications. By automatically sending event data when something happens, they eliminate the need for constant polling and make system integrations more efficient.
For analytics and marketing teams, webhooks play an important role in modern tracking architectures. They make it possible to capture events that occur outside the browser and connect them with advertising and analytics platforms.
When combined with server-side tracking, webhooks help businesses build more reliable data pipelines, improve conversion attribution, and gain a clearer understanding of the customer journey.
If your goal is to track more events and automate data flows across systems, implementing webhooks is a great place to start.