What is the difference between resource and endpoint?

The terms resource and endpoint are often used synonymously. But in fact they do not mean the same thing.

The term endpoint is focused on the URL that is used to make a request.
The term resource is focused on the data set that is returned by a request.

Now, the same resource can often be accessed by multiple different endpoints.
Also the same endpoint can return different resources, depending on a query string.

Let us see some examples:

Different endpoints accessing the same resource

Have a look at the following examples of different endpoints:

/api/companies/5/employees/3
/api/v2/companies/5/employees/3
/api/employees/3

They obviously could all access the very same resource in a given API.

Also an existing API could be changed completely. This could lead to new endpoints that would access the same old resources using totally new and different URLs:

/api/employees/3
/new_api/staff/3

One endpoint accessing different resources

If your endpoint returns a collection, you could implement searching/filtering/sorting using query strings. As a result the following URLs all use the same endpoint (/api/companies), but they can return different resources (or resource collections, which by definition are resources in themselves):

/api/companies
/api/companies?sort=name_asc
/api/companies?location=germany
/api/companies?search=siemens

REST

Resource is a RESTful subset of Endpoint.

An endpoint by itself is the location where a service can be accessed:

https://www.google.com    # Serves HTML
8.8.8.8                   # Serves DNS
/services/service.asmx    # Serves an ASP.NET Web Service

A resource refers to one or more nouns being served, represented in namespaced fashion, because it is easy for humans to comprehend:

/api/users/johnny         # Look up johnny from a users collection.
/v2/books/1234            # Get book with ID 1234 in API v2 schema.

All of the above could be considered service endpoints, but only the bottom group would be considered resources, RESTfully speaking. The top group is not expressive regarding the content it provides.

A REST request is like a sentence composed of nouns (resources) and verbs (HTTP methods):

• GET (method) the user named johnny (resource).
• DELETE (method) the book with id 1234 (resource).

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Non-REST

Endpoint typically refers to a service, but resource could mean a lot of things. Here are some examples of resource that are dependent on the context they're used in.

URL: Uniform "Resource" Locator

• Could be RESTful, but often is not. In this case, endpoint is almost synonymous.

Resource Management

• In GCP / AWS, resource is used in reference to cloud infrastructure.
• In general computing, a resource is a reference to a component with limited availability.

Dictionary

• The definitions provide many more uses of the word.

Something that can be used to help you:

The library was a valuable resource, and he frequently made use of it.

Resources are natural substances such as water and wood which are valuable in supporting life:

[ pl ] The earth has limited resources, and if we don’t recycle them we use them up.

Resources are also things of value such as money or possessions that you can use when you need them:

[ pl ] The government doesn’t have the resources to hire the number of teachers needed.

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The Moral

The term resource by definition has a lot of nuance. It all depends on the context its used in.