What is API Management & ESB?

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Woman debating the pros and cons of ESB vs. API management

With new systems, applications, and data sources added on a regular basis, IT environments are growing more complex than ever before. To deal with this complexity, organizations are relying on ESB and API management solutions that decouple IT infrastructure, facilitating information exchange. So which ESB and API management is right for you and why?

It’s no surprise, then, that the API management industry has never been stronger. According to the consulting firm KBV Research, the global API management market will reach $6.2 billion by 2024, with an average growth rate of 28 percent annually.

But what is API management exactly? More importantly, what are the differences between API management and ESBs, another common tool in the enterprise integration space? We’ll give you all the answers in this article.

Here’s what you’ll learn in this comprehensive guide to ESBs and API management:

What is an ESB?

An ESB (enterprise service bus) is a centralized middleware platform that is used to integrate various enterprise systems and applications. ESBs replace the need for point-to-point communication, which is highly complex and not easily scalable.

The ESB is an abstraction layer, acting as a “universal translator” that enables communication between multiple systems speaking a different “language.” When one system has a message to pass on, the ESB translates this message and routes it to the correct recipient.

Here are the main reasons why companies use an ESB:

  • ESBs dramatically simplify the process of integrating multiple heterogeneous IT environments and systems.
  • By mediating communication between separate parts of the environment, ESBs remove the need for different services to translate messages on a point-to-point basis.
  • ESBs include features such as load balancing and failover support that make your IT environment more scalable and resilient.

What is API Management?

API management is the general process of designing, documenting, deploying, and overseeing the various APIs (application programming interfaces) within an enterprise.

The core of an API management solution is known as an API gateway. Like ESBs, API gateways process API calls and act as a mediator or single point of entry, translating messages between different services.

Here are the main reasons why companies use API management:

  • API management solutions make your business IT more flexible and resilient.
  • API management solutions provide insight into how systems communicate and data is exchanged within your enterprise and between third-party services.
  • API management solutions secure your enterprise APIs by protecting them from unauthorized access.

ESB vs. API Management

As you can guess from the above definitions, ESBs and API management share capabilities and functionality—yet despite their similarities, API management and ESBs are two entirely different things.

Here are the main differences between API management and an ESB:

  • API management tools often have additional features and capabilities that are not present with an ESB.
  • API management is more flexible and optimized for newer tech developments such as microservices, whereas ESBs are not.
  • API management solutions are typically consumption-based, while ESBs have an exposure-based model.


Both ESBs and API management solutions are able to expose REST and SOAP interfaces. However, creating such interfaces is not unique to these two tools. Other IT solutions such as application servers, SaaS applications, and mainframe transaction systems are also capable of creating REST interfaces.

So what is the difference between ESBs and API management in terms of features? API management typically involves a much more robust, feature-rich set of capabilities, such as:

  • Limiting the number or rate of calls in order to prevent overloads and crashes.
  • Security and authentication policies to protect APIs from unauthorized access.
  • Load balancing and routing features to optimally send traffic to the best servers.
  • Monitoring and analytics capabilities to assess performance over time, discovering and fixing any lingering issues.
  • Provisioning API keys for software developers.
  • Monetizing APIs that are exposed to third parties and customers.
  • Generating and sharing API documentation.

Another important point of distinction is that ESBs have traditionally run on-premises and worked with legacy infrastructure and technology. However, this is gradually changing, as some ESBs are capable of integrating cloud and SaaS applications.

Agility and Flexibility

Many companies are finding that ESBs are increasingly inadequate for the rapidly changing digital landscape. Instead, they’re turning to agile, modern API management solutions that give them the flexibility and adaptability they need to remain competitive.

One example of the difference between API management and ESBs is their suitability for microservices. The microservices architecture is an application development technique in which software is decomposed into smaller, modular components, each one designated for a specific purpose.

ESBs arose at a time when traditional “monolithic” software applications were breaking down into service-oriented architecture (SOA). However, progress didn’t stop there—microservices are a natural evolution of the SOA concept, offering developers fine-grained control over each service’s functionality.

API management solutions are better for microservices because they don’t suffer from the same brittleness as ESBs do. ESBs are commonly used to implement rigid business logic, strict orchestration, and strong coupling between different applications. However, this rigidity has a downside, making it harder for developers to scale and replace application components.

The difference between API management and ESBs can be summed up like this: ESBs are typically optimized for stability, connecting established business processes that are well-understood. Meanwhile, the best API management solutions are optimized for innovation and creativity, helping to drive business growth.

Consumption and Exposure

Naturally, the different purposes of ESBs and API management have effects on how they’re used in practice.

ESBs are typically managed by the IT department and follow a rigid structure, making them “exposure-centric.” When a new integration is needed, or the business wants to reorganize the flow of information, your IT team needs to make and maintain these changes, which adds more burden to your support obligations.

API management tools, on the other hand, usually follow a “consumption-centric” model. Developers and users alike want the ability to quickly and easily consume new data and services, without being limited by the stringent limitations of an ESB.

Like a highway system, ESBs are reliable and stable, but they may not get you exactly where you need to go. API management solutions enhance the functionality of ESBs by enabling users to consume the information and services they want at any given time.

ESB vs. API Management: Which is the Right Choice for You?

Both API management solutions and ESBs have a common purpose: closer integration between various systems, applications, and data. However, the similarities stop there. In general, API gateways are more agile and flexible, making them better suited for the modern enterprise IT landscape.

Going with an ESB is probably the best route for your company if:

  • Many of your systems and applications remain on-premises.
  • You’re mainly concerned with your internal systems, not external third-party integrations.
  • You prefer a more logical, “exposure-centric” model.

Using an API manager is likely the better choice for your company if:

  • You need access to features and functionality not available with ESBs.
  • You want a more flexible solution that is better suited for e.g. microservices architectures.
  • You prefer a more agile, “consumption-centric” model.

Still need clarity on the topic of API management? Check out our related article in which we compare ESBs with iPaaS (integration platform as a service) solutions.

If you’re looking for a little advice on your own API management capabilities, get in touch with the DreamFactory team today. We’ll discuss your business needs and objectives and set you up with a free trial of the DreamFactory REST API management platform.