Webhook vs API: Similarities and Differences

To succeed at email marketing, email professionals must craft compelling content, target the right audience, and strategically send emails at the opportune moment. Technology has played a significant role in simplifying these tasks, offering a range of tools and software to streamline the process.

However, for email marketers to harness the power of automation and deliver exceptional experiences, understanding two key concepts is crucial: webhooks and APIs. While both deal with data exchange, they serve distinct purposes and function in different ways.

This guide will explore the intricacies of webhooks and APIs, explaining their functionalities and highlighting the key differences between them. By the end, you’ll have a clear understanding of when to leverage each for optimal email marketing success!

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What is a Webhook?

A webhook is a way for one application to provide other applications with real-time information; it is essentially an automated message sent from one app to another when a specific event occurs.

It delivers data to other applications as it happens, meaning you get data immediately. A webhook is a user-defined HTTP callback — a ping or request from a server. 

It is typically triggered by an event. When the specified event occurs, the source site sends an HTTP request to the URL configured for the webhook. 

Webhooks are commonly used to trigger an action in one system in response to an event in another. For example, if you run a website that sells products, you might want to notify your inventory system whenever a purchase is made. You may also wish to send the buyer an email. Webhooks are ideal for these functions. 

When the purchase event occurs, the webhook sends a “POST request,” which is a request message with data enclosed in its body. Your inventory system receives this information about the purchase, and it updates stock levels immediately. A second webhook can inform your email platform that it needs to send the customer a transactional email.

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How Webhooks Work

Each section consists of a sequence, as explained below.

1. Setting Up the Webhook

First, you must configure a webhook by registering a URL — also called an endpoint — with the service you want to receive updates from. This URL is where the service will send HTTP requests when an event occurs.

Next, specify which events should trigger the webhook. For example, you might want to be notified when a new user signs up for your email marketing newsletter, an order is placed on your website, or a specific action is taken.

2. Triggering the Event

When the specified event occurs in the source application (for example, a new user joins your mailing list or purchases a product), the source application recognizes that an event that you’ve subscribed to has taken place.

The source application then creates an HTTP POST request containing data about the event. This request is sent to the URL you provided during the setup.

3. Handling the HTTP Request

Once the destination server receives the HTTP POST request at the specified URL, it processes the data contained in the request. This may involve updating a database, triggering additional processes, or taking other actions based on the received information.

The server typically responds with a status code to acknowledge receipt and processing of the request. For example, a “200 OK” response indicates successful processing.

Webhooks in Action: Example

Here’s a hypothetical scenario: Say you own an online business called “Carpets Inc.” where you sell rugs and carpets via an e-commerce store.

This process occurs every time a webhook is triggered. You can set up similar webhooks to notify you of other actions that happen on your website or your e-commerce platform.

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What is an API?

An API, or Application Programming Interface, is a set of rules and protocols that allow software to interact with each other. Think of it as a software layer facilitating communication between an app and a web server.

APIs define the methods and data formats that applications can use for two-way communication. This allows for the integration of different systems and the sharing of data/functionality.

There are many ways to classify APIs, but they’re typically organized into the following categories:

Type	Description
Public/Open API	Publicly accessible, allowing any developer to use it.
Partner API	Accessible only to authorized partners or clients.
Internal/Local API	Used exclusively within an organization for internal applications.
Composite API	Combines multiple APIs to provide a unified interface.

If you hear about APIs classified as REST (Representational State Transfer) or SOAP (Simple Object Access Protocol), they are referring to the protocols used.

The Building Blocks of APIs

To understand how APIs function, it’s essential to grasp the fundamental building blocks that govern their interactions. These components dictate how data is requested, processed, and delivered.

To accurately understand APIs, you must be familiar with these concepts:

Concept	Explanation
Endpoint	A specific URL where API services can be accessed; each endpoint corresponds to a different function or resource provided by the API.
Requests	The action initiated by the client to interact with the API, typically including an endpoint, HTTP method, headers, or data.
Responses	The data and status codes sent back by the API server in reply to a client’s request, indicating the result of the request.
Methods	HTTP methods used to specify actions: GET (retrieve data), POST (create new data), PUT (update data), DELETE (remove data).
Headers	Additional information sent with the request or response, such as content type, authentication tokens, and metadata.
Authentication	The process of verifying the identity of the client, often using API keys, OAuth tokens, or other credentials.
Authorization	The process of verifying that the authenticated client has permission to perform the requested action.
Data Formats	Standard formats for data exchange, such as JSON or XML, ensuring compatibility between the client and server.

While most of these elements are under the hood, you still need to know about them; the knowledge will be helpful when troubleshooting API issues.

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How Do APIs Work?

While the actual methodology of how APIs work is highly technical and complex, we can break it down into two stages for simplicity. 

Stage 1: Request Received

The API server receives the request, including the endpoint, HTTP method, headers, and any data sent by the client.

Next, the server routes the request to the appropriate handler based on the endpoint and HTTP method. The handler processes the request, which might involve interacting with a database, performing business logic, or calling other services.

If the request involves retrieving or modifying data, the server performs all necessary operations. For example, a GET request typically involves querying a database to retrieve records, while a POST request saves new data to the database.

Stage 2: Server Response

After processing the request, the server generates a response. 

This includes a status code (such as 200 for success, 404 for not found, or 500 for server error), headers, and the response body containing the requested data or the result of the operation.

The response data is typically formatted in JSON or XML to ensure compatibility with the client. The server sends the response back to the client, including the status code, headers, and any data.

API in Action: Example

Like the webhooks example above, let’s assume you own an imaginary online business called Carpets Inc., selling rugs and carpets. Customers often add items to their cart but don’t complete the purchase.

In this situation, you can use an API to integrate your e-commerce platform with an email marketing service to send them an abandoned cart email.

Such API calls flow in high volume between apps and servers, exchanging data.

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Webhook and API: Main Similarities

Webhooks and APIs can appear similar in many ways. They’re both used for marketing automation and transferring information, plus there are similarities in workflow.

As you can tell by the list above, the similarities between webhooks and APIs are superficial. In the next section, we outline why webhooks can never replace API use and vice versa. 

As a modern-day marketer, you need both functionalities to be effective at your job — let’s learn how.

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Webhook vs API: The Differences

While webhooks and APIs have many things in common, it’s the distinct differences in functionality and use cases that determine the best scenarios for their application.

This table breaks down the differentiating aspects of webhooks and APIs:

Aspect	Webhooks	APIs
Trigger	Event-driven; initiated by the server when an event occurs.	Request-driven; initiated by the client to perform specific actions.
Data flow	Push data from the server to the client automatically when an event occurs.	Require the client to pull data from the server by making explicit requests.
Real-time updates	Provide real-time updates by immediately sending data to the client upon event occurrence.	May not provide real-time updates; the client must periodically poll the API for new data.
Efficiency	More efficient for real-time notifications.	Less efficient as polling is required frequently to check for updates.
Use cases	Ideal for scenarios such as payment confirmations, issue tracking updates, real-time messaging.	Better suited for situations where the client needs to retrieve, create, update, or delete data on demand.
Setup	Require setting up a listener endpoint on the client side to receive incoming data.	Require the client to make HTTP requests to the server’s endpoints as needed.
Control	The server controls when and what data is sent based on events.	The client has control over when to make requests and what actions to perform.
Scalability	More challenging to scale due to handling incoming requests from multiple sources in real time.	Generally easier to scale as clients initiate requests, allowing the server to manage load more predictably.
Error-handling	Require robust error handling and retry mechanisms to ensure data is delivered successfully.	Errors can be handled immediately in response to the client’s request, with retries managed by the client.

In the next section, we give examples that highlight different uses for webhooks and APIs.

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Webhook vs API: When to Use Which

Webhooks and APIs are powerful tools that enable seamless communication. Understanding their unique characteristics and use cases is crucial if you want to leverage them effectively. 

By knowing when to use webhooks for real-time updates and APIs for on-demand data retrieval, you can optimize your automation processes.

When to Use Webhooks

Examples of Webhooks

When to Use APIs

API: Examples

Next, let’s check out the roles played by APIs and webhooks in email marketing.

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Webhooks and APIs Use in Email Marketing

Webhooks and APIs are instrumental in modern email marketing. 

APIs allow for deep integration of email platforms with other systems, such as CRM (Customer relationship management) systems. With APIs, marketers can automate tasks, synchronize data, and build custom applications. 

For instance, an email service provider (ESP) might offer an API to access subscriber data, send campaigns, or retrieve detailed email campaign metrics. 

On the other hand, webhooks act as real-time messengers. They enable ESPs to send instant notifications about email events, such as opens, clicks, or bounces, to external applications. Webhooks empower marketers to set up automated workflows, update CRM records, or trigger personalized actions based on subscriber behavior. 

Together, APIs and webhooks form a powerful combination for creating dynamic and effective email marketing campaigns.

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Access Webhooks and API With Ease at Campaign Refinery

Campaign Refinery‘s robust API empowers email marketers to seamlessly integrate their email campaigns with other marketing tools and platforms. By accessing and manipulating data, marketers can automate tasks, update their integrated marketing tools, and gain deeper insights into email performance. 

For instance, you can synchronize email subscriber data between your CRM and Campaign Refinery, create custom reporting dashboards, or trigger personalized email workflows based on specific actions.

Complementing the API, Campaign Refinery’s webhooks enable real-time communication between your email platform and external applications. With webhooks, you can receive instant notifications about actions your email subscribers take, such as opens, clicks, and unsubscribes.

This allows for dynamic responses and actions, such as updating CRM records, triggering retargeting campaigns, or sending SMS messages based on email engagement. 

We will also soon add the ability to schedule and send broadcasts over API. Our customers are excited about this!

By utilizing both API and webhooks at Campaign Refinery, email marketers can create highly automated and efficient campaigns that deliver exceptional results.
Unlock your best email marketing performance today with Campaign Refinery — apply here to become a customer!