HubSpot Guide to Web Services vs API

Understanding the difference between web services and APIs is essential if you use HubSpot or any modern platform to connect apps, share data, or automate workflows. Many teams treat these terms as interchangeable, but they are not the same thing, and choosing the right approach affects performance, security, and scalability.

This guide explains what web services and APIs are, how they relate to each other, and when to use each pattern for integrations and development.

What Is a Web Service?

A web service is a standardized way for two applications to communicate over a network, usually the internet. It exposes functionality or data that other systems can request using common web protocols.

Key traits of a web service include:

• Runs on a remote server and is accessed over HTTP, HTTPS, or similar protocols.
• Exposes specific operations, such as getCustomer or submitOrder.
• Relies on agreed formats and contracts, such as XML schemas.
• Often designed to be platform-independent, so different tech stacks can talk to it.

In a typical setup, a client application sends a request to the web service, which processes the input, interacts with its own data or logic, and returns a structured response.

How Web Services Work

Most traditional web services follow a request–response model. A client calls a specific endpoint with required parameters, and the service returns a response in a defined format.

Classic Web Service Stack

Historically, three concepts often appear together when discussing web services:

• SOAP (Simple Object Access Protocol) – A protocol that defines how messages are formatted and transmitted, usually using XML.
• WSDL (Web Services Description Language) – An XML-based document that describes what the service does, what operations exist, and how to call them.
• UDDI (Universal Description, Discovery, and Integration) – A directory for registering and discovering available web services.

These standards give web services a strong contract so that client applications know exactly how to interact with them.

Types of Web Services

Common categories of web services include:

• SOAP-based web services – Use SOAP envelopes, strict XML schemas, and detailed WSDL contracts. They are common in enterprise systems that require strong typing and formal standards.
• REST-style web services – Use standard HTTP verbs and URLs to operate on resources. These are often easier to implement and more flexible.

While many people now call REST-style web services simply “APIs,” they still follow the core idea of exposing remote functionality over the web.

What Is an API?

An API (Application Programming Interface) is a set of rules and definitions that allow one piece of software to interact with another. Unlike web services, APIs are not limited to web protocols and can exist within a desktop application, an operating system, or a cloud platform.

Key characteristics of an API include:

• Defines how functions, methods, or endpoints can be used.
• Specifies input parameters and the structure of outputs.
• Hides internal implementation details from the consumer.
• Can use many transports, including HTTP, libraries, or system calls.

In web development, people often mean a web API when they say API, but the concept is broader and applies anywhere two software components communicate through defined interfaces.

How Web APIs Work

A web API is an API exposed over HTTP or HTTPS, typically returning data in JSON or XML. It blends the idea of an API with the web-based communication model of web services.

Common Web API Styles

Popular patterns for web APIs include:

• REST (Representational State Transfer)
  • Uses standard HTTP methods: GET, POST, PUT, PATCH, DELETE.
  • Focuses on resources identified by URLs.
  • Often returns JSON, making it easy to use in browsers and mobile apps.
• GraphQL
  • Clients send flexible queries to request exactly the data they need.
  • Uses a single endpoint and a typed schema.
• RPC-style APIs
  • Focus on calling remote procedures or actions directly.
  • Can use HTTP, gRPC, or other transports.

These web APIs may or may not be considered web services, depending on how strictly you define the term, but they serve the same basic purpose of enabling application communication.

HubSpot Context: Web Services vs APIs

Many modern platforms, such as HubSpot, are built around APIs rather than older SOAP-centric web services. Understanding that relationship helps when you design integrations or choose tools.

Is Every API a Web Service?

No. An API is a broader concept. Some APIs are entirely local, such as a file system API or a graphics API, and never use the web. Those are not web services.

Is Every Web Service an API?

Yes. A web service exposes an interface that other applications can use, which makes it a type of API. The web service is just an API delivered over web protocols with additional standards around descriptions and discovery.

Key Differences Between Web Services and APIs

Although they overlap, web services and APIs emphasize different aspects of integration.

Transport and Scope

• Web services – Always use network protocols such as HTTP or HTTPS. They are inherently remote.
• APIs – Can be local or remote and use any communication mechanism available to the environment.

Standards and Contracts

• Web services – Often use formal standards like SOAP, WSDL, and XML schemas. These provide explicit contracts and strong typing.
• Web APIs – Often more lightweight, relying on conventions (for example, REST) rather than heavy specifications.

Use Cases

• Web services – Common in enterprise, legacy integrations, or systems that need strict specifications and governance.
• Web APIs – Common in SaaS platforms, mobile apps, and microservices where flexibility and speed matter.

When to Use Web Services vs APIs

Choosing between a traditional web service and a more flexible API depends on requirements and existing infrastructure.

Choose a Web Service When

• You must integrate with legacy enterprise systems that already expose SOAP-based endpoints.
• Your organization or partners require strict contracts and formal documentation.
• You rely on tools that generate client code directly from WSDL files.

Choose a Web API When

• You are building modern web or mobile applications.
• You prioritize ease of use, developer experience, and rapid iteration.
• You want to use common patterns like REST and JSON for broad compatibility.

Platforms like HubSpot lean on web APIs to make it easier for developers to integrate with CRM, marketing, or sales data using standard HTTP calls.

Practical Examples and Next Steps

To solidify the concepts, consider these scenarios:

• Enterprise resource planning system – Might expose SOAP-based web services to manage inventory, billing, and orders.
• Modern marketing platform – Might expose RESTful APIs for contacts, campaigns, and analytics to connect with other tools.
• Custom integration layer – Might consume both SOAP web services and REST APIs and unify them behind a single interface.

For a deeper explanation of the distinctions and historical context, you can review the original article on web services vs API on this reference page.

HubSpot Style Takeaways for Developers

Whether you are connecting to a CRM, building marketing automation, or linking analytics tools, clear interfaces and good documentation matter more than the specific label of web service or API.

• Focus on explicit contracts and versioning.
• Use secure transport (HTTPS) for all remote calls.
• Prefer consistent resource naming and error handling patterns.
• Document request and response examples clearly for each endpoint or operation.

If you want strategic help planning integrations, technical SEO, or content architecture around APIs and web services, you can learn more from Consultevo’s consulting services.

Conclusion: Applying HubSpot-Level Clarity

Web services and APIs solve the same fundamental problem: letting software systems talk to each other. A web service is a web-based, standards-driven type of API, while an API is any defined interface between components, whether local or remote.

By understanding how they differ in scope, transport, and standards, development and marketing teams can plan integrations that are easier to build, maintain, and scale across all their tools and platforms.

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