UE5 API Calls with C++

What You Will Build

• A clean UE5.6 C++ project for HTTP API work
• A Blueprint Function Library for reusable API calls
• A Blueprint-friendly delegate for async responses
• A static C++ function that sends HTTP GET requests
• A Blueprint node that returns status code and response text
• A simple in-game test using a public JSON endpoint

Why This Approach Is Good for Beginners

API tutorials often fail beginners in one of two ways:

• they stay too abstract and never produce a working result
• they bury the useful logic under too much architecture too early

This approach avoids both problems.

It is good for beginners because:

• the logic lives in one obvious place
• the Blueprint node is reusable anywhere in the project
• the response is returned in a Blueprint-friendly way
• you learn Unreal’s actual HTTP module instead of depending on third-party tools

What This Tutorial Does and Does Not Cover

This tutorial focuses on the cleanest useful starting point:

• GET requests
• async HTTP flow
• Blueprint callback integration
• basic response printing

It does not go deep yet into:

• POST requests
• DELETE requests
• JSON deserialization into structs
• authentication systems
• robust production error handling

That is the right decision. Beginners need the first clean win before they start stacking complexity.

Step 1: Create a Clean C++ Project

Start by creating a new Unreal Engine 5.6 C++ project.

Recommended setup:

• Template: Blank
• Project Type: C++
• Name: UnrealAPICallSample

A clean C++ starter project is the best choice here because it removes unrelated gameplay noise and keeps the API work easy to isolate.

Why a Blank C++ Project Is Better Here

You could add this to a bigger game project later, obviously. But for learning, a blank C++ project is cleaner because:

• you are not distracted by unrelated Blueprints
• the Build.cs file is easy to inspect
• the C++ class generation flow stays simple
• testing is more direct

This is the right place to learn the pattern.

Step 2: Disable Live Coding

Inside Unreal, go to:

Edit → Editor Preferences → Live Coding

Disable:

Enable Live Coding

This is optional, but it is a good idea when doing early C++ setup work. Live Coding can sometimes create confusion or unstable behavior during basic iteration, especially for beginners who are still learning what changed and where.

A clean rebuild is slower, but more predictable.

Step 3: Create a Blueprint Function Library

In Unreal, go to:

Tools → New C++ Class

Switch to:

All Classes

Search for:

Blueprint Function Library

Create a class such as:

MyBlueprintFunctionLibrary

or any cleaner name you prefer for your project.

Why a Blueprint Function Library Is the Right Choice

A Blueprint Function Library is a great fit because the function you are building is:

• static
• reusable
• not tied to one actor instance
• useful from many different Blueprints

That makes it a much better choice than stuffing API logic into some random Actor or Widget Blueprint just because it was already open.

Step 4: Declare a Blueprint-Friendly Delegate

In your generated header file, declare a dynamic delegate that can send the API result back to Blueprint.

Example:

DECLARE_DYNAMIC_DELEGATE_TwoParams(FOnAPIResponse, int32, StatusCode, const FString&, Response);

This gives you a callback that can return:

• the HTTP status code
• the response body as a string

That is enough for a basic and very practical GET request workflow.

Why a Delegate Is Necessary

HTTP requests are asynchronous. That means Unreal does not have the response immediately at the moment you call the function.

So this will not work as a normal synchronous return value pattern.

Instead, you call the request now and receive the result later through a callback. That is exactly why the delegate exists.

Step 5: Declare the Static Function in the Header

Inside the public section of the Blueprint Function Library, declare a Blueprint-callable static function.

Example:

UFUNCTION(BlueprintCallable, Category="RambodDev|API")
static void FetchDataFromURL(const FString& URL, const FOnAPIResponse& Callback);

This is the function that will appear as a Blueprint node later.

It takes:

• a URL string
• a callback delegate

Why the Function Returns Void

Beginners often expect API functions to just return the response directly. That is not how async HTTP works here.

The function returns void because:

• it starts the request
• the response arrives later
• the delegate handles the result

That is the correct pattern for this kind of node.

Step 6: Generate the CPP Definition

Generate the function definition in the CPP file using your IDE or do it manually.

Then add the required includes at the top of the CPP file:

#include "HttpModule.h"
#include "Interfaces/IHttpResponse.h"
#include "Http.h"

Without these headers, the HTTP types and functions will not compile.

Step 7: Implement the HTTP GET Request

Inside the CPP function, create the HTTP request using Unreal’s built-in HTTP module.

The core structure looks like this:

void UMyBlueprintFunctionLibrary::FetchDataFromURL(const FString& URL, const FOnAPIResponse& Callback)
{
    if (!FHttpModule::Get().IsHttpEnabled()) return;

    TSharedRef<IHttpRequest, ESPMode::ThreadSafe> Request = FHttpModule::Get().CreateRequest();
    Request->SetVerb("GET");
    Request->SetURL(URL);

    Request->OnProcessRequestComplete().BindLambda(
        [Callback](FHttpRequestPtr Request, FHttpResponsePtr Response, bool bSuccess)
        {
            int32 StatusCode = bSuccess && Response.IsValid() ? Response->GetResponseCode() : -1;
            FString Result = bSuccess && Response.IsValid() ? Response->GetContentAsString() : TEXT("Request failed");

            Callback.ExecuteIfBound(StatusCode, Result);
        }
    );

    Request->ProcessRequest();
}

That is the heart of the entire beginner-friendly API setup.

How This C++ Function Works

The logic is simple:

1. Check that HTTP is enabled.
2. Create a request object.
3. Set the request method to GET.
4. Assign the target URL.
5. Bind a lambda to handle the response when it arrives.
6. Extract the status code and response string.
7. Execute the Blueprint callback if it is bound.
8. Send the request.

That is it. No plugin required.

Step 8: Optional Headers

You can also attach headers if the API needs them.

Example:

// Request->SetHeader(TEXT("Content-Type"), TEXT("application/json"));
// Request->SetHeader(TEXT("Authorization"), TEXT("Bearer YOUR_API_KEY"));

For the basic tutorial, you do not need them yet. But it is useful to know where they belong.

Step 9: Update Build.cs

Open your project Build.cs file and add the required dependency modules.

Example:

PublicDependencyModuleNames.AddRange(
    new string[] { "Core", "CoreUObject", "Engine", "InputCore", "HTTP", "Json" }
);

At minimum, HTTP is required for this tutorial. Json is useful because it is the natural next step once you start parsing API responses properly.

Why Build.cs Matters Here

If the required modules are not declared in Build.cs, the code either will not compile or will fail to link correctly.

This is standard Unreal C++ setup work. Ignore it and the whole thing breaks.

Step 10: Build the Project

Build the project in Rider, Visual Studio, or your preferred Unreal-compatible IDE.

If the code and dependencies are correct, Unreal should compile the project and expose the function to Blueprints.

Step 11: Create a Simple Test Level

Open Unreal and create an empty test level, or use a minimal existing map for the API check.

The point is to remove distractions. You are testing the HTTP node, not gameplay systems.

Step 12: Open the Level Blueprint

Open the Level Blueprint and add:

Event Begin Play

This is enough for a first API test.

Step 13: Add the Blueprint Node

Search for your function:

Fetch Data From URL

Add it to the Level Blueprint and connect:

Event Begin Play → Fetch Data From URL

Then give it a safe test endpoint such as:

https://jsonplaceholder.typicode.com/todos/1

This is a common public test endpoint that returns simple JSON.

Step 14: Use the Callback in Blueprint

From the callback pin, create the callback event and use the output values.

For a first test, take:

Response

and connect it to:

Print String

That is enough to prove the API call is working and that the response is reaching Blueprint correctly.

Step 15: Press Play and Verify the Response

Hit Play.

If the setup is correct, you should see the response JSON printed on screen.

That confirms:

• the HTTP request was sent
• the response was received
• the delegate callback fired
• Blueprint received the result correctly

That is a real working Unreal API integration.

What the Final Result Gives You

After finishing this setup, you have:

• a reusable API call node
• a clean Blueprint callback pattern
• a base you can expand into POST, headers, JSON parsing, and more
• a much better understanding of how Unreal handles HTTP requests internally

That is a lot more useful than just copying a random code snippet without understanding it.

Real-World Use Cases

Once this pattern is working, you can use it for:

• loading player profile data
• fetching leaderboards
• checking backend service health
• loading configuration from a web service
• connecting UI panels to live data
• building tools or dashboards inside Unreal

The core pattern stays the same.

Common Problem: The Node Does Not Appear in Blueprint

If the Blueprint node does not show up:

• make sure the project compiled successfully
• make sure the function is marked BlueprintCallable
• make sure the class is a Blueprint Function Library
• restart Unreal if reflection did not refresh properly

Usually this is either a compile issue or a macro issue.

Common Problem: Build Errors Around HTTP Types

If Unreal does not recognize HTTP types:

• check your includes
• check that HTTP is added to Build.cs
• rebuild the project cleanly

Missing module dependencies are the usual cause here.

Common Problem: The Request Fails

If the callback fires but the request fails:

• verify the URL is valid
• use a public test endpoint first
• check internet access
• check if the API requires headers or authentication
• print the status code to diagnose the response properly

Do not guess. Print the status code and inspect the response.

Common Problem: Expecting a Synchronous Return Value

This is a beginner trap.

If you try to treat the HTTP function like a normal immediate function call, you are misunderstanding the async model. The response arrives later. That is why the delegate exists.

Once you accept that, the whole pattern becomes much easier to reason about.

Why This Is a Strong Foundation

This setup is strong because it uses Unreal’s built-in systems the right way:

• HTTP module for the request
• Blueprint Function Library for global reuse
• Dynamic delegate for Blueprint callback flow
• Build.cs modules declared correctly

That gives you a practical beginner foundation without locking you into a plugin dependency.

What to Build Next

Once this basic GET request works, the most useful next upgrades are:

• POST requests
• custom headers
• Bearer authentication
• JSON parsing into usable fields
• response validation
• better error reporting
• wrapping results into Blueprint-friendly structs

But the first step is this: make one clean request and get the result back into Blueprint.

Conclusion

In this tutorial, you created a clean Unreal Engine 5.6 C++ API setup, built a Blueprint Function Library, declared a Blueprint-friendly callback delegate, implemented an async HTTP GET request using Unreal’s HTTP module, updated Build.cs, and tested the result in a Blueprint by printing live API data on screen.

That gives you a real API integration foundation in Unreal without plugins and without overcomplicating the workflow.

Watch the full video on YouTube: Easiest Way To Use APIs In Unreal Engine For Beginners

Download the sample project: UnrealAPICallSample on GitHub

Subscribe for more Unreal Engine tutorials: Subscribe to Rambod on YouTube

Resources

• GitHub: UnrealAPICallSample
• YouTube Tutorial

Frequently Asked Questions

How do I call an API in Unreal Engine without plugins?

Use Unreal’s built-in HTTP module in C++, expose a static function through a Blueprint Function Library, and return results through a dynamic delegate callback.

Why use a Blueprint Function Library for API calls?

Because it makes the function global, reusable, and easy to call from any Blueprint without depending on a specific actor instance.

Why is the API function asynchronous?

HTTP requests do not return instantly. Unreal sends the request now and receives the response later, so the result must come back through a callback.

What modules do I need in Build.cs?

At minimum, you need HTTP. Json is also useful if you plan to parse JSON responses next.

Can I use this same setup for POST requests too?

Yes. The same structure can be extended for POST, DELETE, headers, body content, and JSON handling.

What is the easiest test endpoint for this?

A public test endpoint like jsonplaceholder is a good starting point because it returns predictable JSON without requiring authentication.