What Are the Types of APIs and Their Differences?

Ever used a POST request when you should have used PUT? This common mistake can lead to duplicated data and break caching mechanisms. Selecting the correct HTTP method is more than a technical detail; it's a strategic choice affecting your application's performance, reliability, and architecture. As 74% of organizations now adopt an API-first approach, mastering these foundational concepts is more critical than ever.

This guide covers the seven core HTTP methods for daily use: GET, POST, PUT, DELETE, PATCH, HEAD, and OPTIONS. We will analyze how the right selection improves performance through caching, ensures reliability with idempotency, and strengthens your API's design.

What Are API Request Methods?

API request methods, often called HTTP verbs, are commands that specify the action a client wants to perform on a server resource. Making the right type of API call ensures that clients, servers, and intermediaries (like caches and proxies) all understand the intent behind a request.

Most modern web services are built on RESTful APIs, which use these standard HTTP methods as their foundation. The Hypertext Transfer Protocol (HTTP) itself, as defined by the Internet Engineering Task Force (IETF), gives each method built-in semantics, including three critical properties: safety, idempotency, and cacheability.

• Safety: A method is "safe" if it is essentially read-only and does not alter the state of the resource on the server.

• Idempotency: A method is "idempotent" if making the same request multiple times produces the same result as making it once.

• Cacheability: A method is "cacheable" if its response can be stored to be reused for subsequent, identical requests.

Breakdown of Each HTTP Method

Let's break down each of the core API request types. For each one, we will cover its definition, primary purpose, key properties, and a practical example.

a. GET

The GET method retrieves a representation of a specified resource. It is the most common method and should only be used for read-only operations. Importantly, a GET request should not include a body; all required data should be passed in the URL.

• Purpose: Use GET to fetch data, such as a user's profile, a list of products, or a specific blog post.

• Properties:

  • Safe: Yes

  • Idempotent: Yes

  • Cacheable: Yes

• Scenario: You need to display user information on a profile page. You send a GET request to an endpoint like /users/{id} to retrieve that data.

b. POST

The POST method sends data to a server to create a new resource or process a representation of a resource. Its effect is determined by the server.

• Purpose: Use POST for creating new entities, like a new user account or a forum post. It's also used for actions that don't fit other methods, such as submitting a web form.

• Properties:

  • Safe: No

  • Idempotent: No

  • Cacheable: Only in specific cases, but this is rarely implemented.

• Scenario: A user fills out a registration form. Your application sends a POST request with the user's details to the /users endpoint to create a new account.

c. PUT

The PUT method creates a new resource or replaces a target resource with the request payload. The key difference from POST is that PUT is idempotent and the client specifies the resource's URI.

• Purpose: Use PUT when you need to completely replace an existing resource. For example, updating a user's entire profile with new information.

• Properties:

  • Safe: No

  • Idempotent: Yes

  • Cacheable: No

• Scenario: A user updates their profile settings, replacing all their old information. Your application sends a PUT request to /users/{id} with the complete, updated user object.

d. DELETE

The DELETE method removes a specified resource. It is a straightforward way to request the deletion of an entity.

• Purpose: Use DELETE to remove a resource, such as deleting a user's account, a specific post, or an item from a shopping cart.

• Properties:

  • Safe: No

  • Idempotent: Yes

  • Cacheable: No

• Scenario: A user decides to delete one of their blog posts. Your application sends a DELETE request to the /posts/{id} endpoint to remove it. If the user sends the same request again by mistake, the outcome remains the same: the post is gone, and the system does not produce an error.

e. PATCH

The PATCH method applies partial modifications to a resource. Unlike PUT, you only need to send the data you want to change, making it more efficient for updates.

• Purpose: Use PATCH to update a single field of a resource, like changing a user's email address without resending their entire profile.

• Properties:

  • Safe: No

  • Idempotent: No (by default, but can be designed to be)

  • Cacheable: Sometimes

• Scenario: A user updates only their phone number. Your application sends a PATCH request to /users/{id} with just the new phone number.

f. HEAD

The HEAD method is identical to GET, but it does not return a response body. It only fetches the headers of a resource.

• Purpose: Use HEAD to check a resource's metadata without downloading its content. This is great for verifying if a resource exists, checking its size via the Content-Length header, or seeing when it was last modified.

• Properties:

  • Safe: Yes

  • Idempotent: Yes

  • Cacheable: Yes

• Scenario: Before downloading a large file, you want to check its size. You send a HEAD request to the file's URL to get its headers.

g. OPTIONS

The OPTIONS method describes the communication options for the target resource. It lets a client determine which methods and headers a server supports for a specific URL.

• Purpose: 

  • CORS Pre-flight Requests: A primary use is for Cross-Origin Resource Sharing (CORS). A browser automatically sends an OPTIONS request to check for permissions before sending a complex cross-origin request (like a PUT or DELETE). This initial check is known as a pre-flight request.

  • API Discovery: It's also useful for API documentation and discovery. A client can issue an OPTIONS request to an endpoint to dynamically determine which HTTP methods (GET, POST, DELETE, etc.) the server allows for that resource.

• Properties:

  • Safe: Yes

  • Idempotent: Yes

  • Cacheable: No

• Scenario: Your frontend application, hosted on mydomain.com, needs to send a DELETE request to an API on api.anotherdomain.com. The browser automatically sends an OPTIONS request first to ensure the server allows this action.

Why These Distinctions Matter

These distinctions are not academic; they have profound architectural implications. Understanding the different API request types is key to building resilient and performant systems.

• Safe Methods are Read-Only: Safe methods (GET, HEAD, OPTIONS) should never change data. This contract allows clients, proxies, and search engine crawlers to make these requests without fear of causing unintended side effects. Misusing a GET request to modify data is a common anti-pattern that introduces serious security and reliability risks.

• Idempotent Methods Guarantee Consistent Results: Idempotent methods (GET, PUT, DELETE) are crucial for error handling. If a network error occurs during a PUT request, you can safely send it again without worrying about creating a duplicate resource. This predictability is vital in distributed systems where failures are inevitable. Recent studies show API downtime increased by 60% year-over-year between 2024 and 2025, underscoring the need for resilient design patterns like idempotency.

• Caching Opportunities Boost Performance: Caching is one of the most effective ways to improve application speed. GET and HEAD responses are cacheable by default, allowing browsers and CDNs to serve content without hitting your origin server. This reduces latency for users and decreases the load on your infrastructure. In contrast, methods that modify data (POST, PUT, PATCH, DELETE) correctly invalidate caches to prevent users from seeing stale information.

When to Use Each Method

Choosing the right method clarifies your intent and leads to a more predictable API. Here is a simple decision guide to help you select the appropriate one from the available API request types.

• Choose GET when you are retrieving data without any side effects.

• Use POST to create a new resource where the server determines the final URL.

• Use PUT to create or fully replace a resource at a client-specified URL.

• Select PATCH to apply a partial update to an existing resource.

• Use DELETE to permanently remove a resource.

• Choose HEAD when you only need the resource's metadata (headers), not its body.

• Use OPTIONS to check which actions are allowed on a resource endpoint.

Real-World Examples

Let's see how these API request types come together in a typical e-commerce application.

• Browsing Products: A user views a list of products. The frontend sends a GET /products request to fetch the data. This is a safe and cacheable operation.

• Adding to Cart: The user adds an item to their shopping cart. The application sends a POST /cart request with the product ID. This is not idempotent; sending it twice adds two items.

• Updating Account: The user changes their shipping address in their profile. A PATCH /account request is sent with only the updated address fields. This is more efficient than sending the entire account object.

• Replacing Product Details: An administrator replaces an entire product's details from a dashboard. A PUT /products/{id} request is sent containing the complete new representation of the product. This is idempotent, as sending it repeatedly will result in the same final state.

• Removing a User: An administrator deletes a user account. The system sends a DELETE /user/{id} request. This is also an idempotent action

We strongly recommend using tools like Postman or Insomnia to test these different API request types. These tools allow you to manually craft requests, inspect responses, and validate that your API behaves exactly as expected.

Conclusion

Mastering API request types is a core competency for any developer building for the web. Picking the right method provides clarity, improves performance, and builds a robust, predictable system. It moves your codebase architecture from being merely functional to being truly professional.

As you design your next API, we encourage you to think critically about idempotency, safety, and caching. By embracing these foundational principles of HTTP, you will build applications that are not only powerful but also resilient, scalable, and ready for the future.

FAQs

1) What are the four types of requests?

Often referring to CRUD, they are GET (read), POST (create), PUT (update/replace), and DELETE (remove). Many include PATCH for partial updates.

2) What are the 5 types of HTTP requests? 

The most common five HTTP methods are GET, POST, PUT, PATCH, DELETE. These form the core of RESTful APIs.

3) How many types of API requests are there? 

Technically, HTTP defines many (GET, POST, PUT, DELETE, PATCH, HEAD, OPTIONS, CONNECT, TRACE, etc.). But in daily API work, developers usually focus on GET, POST, PUT, PATCH, DELETE, HEAD, and OPTIONS.

4) What are the 5 API methods?

GET, POST, PUT, PATCH, DELETE—those are the five core methods you’ll use in most APIs.