LambdaLink

LambdaLink connects your game to AWS Lambda without a separate backend SDK or web layer. Put your server logic - score validation, rewards, matchmaking rules, purchases, AI calls - into Lambda functions and call them straight from Blueprints or C++.

Invoke Lambda sends a JSON payload and returns the function's response, status, executed version and, optionally, the tail of its log. Event invocations queue work and return immediately, and Dry Run checks permissions without running anything. Invoke Lambda Stream receives response-streaming functions piece by piece, so long AI answers or progress reports appear while they are produced. Invoke Lambda Batch runs one function for many payloads in parallel and returns every result in order.

Send Signed Request signs any HTTPS call with AWS Signature Version 4 using the same credentials. Use it for API Gateway routes with IAM authorization, Lambda function URLs or other AWS endpoints.

Players get credentials from an Amazon Cognito identity pool: as guests, or signed in with a token from a Cognito user pool, Google, Apple, Facebook or any OpenID provider through Set Login Token. Static keys and the default AWS credential chain are available for development, dedicated servers and tools. Requests run on background worker threads with automatic retries, so the game thread never blocks, and every result arrives back on the game thread.

Struct To JSON, JSON To Struct and Get JSON Field turn payloads into Blueprint structs and values without extra plugins.

LambdaLink is part of the Alpha XP AWS collection for Unreal Engine 4.27 and 5.8. It includes the AWS SDK for C++ prebuilt for Win64, Linux and Android, ships with styled HTML documentation, and is compiled warning-free against clean UE 4.27 and UE 5.8 projects.

Key features

• Invoke Lambda: Request / Response, Event (fire and forget) and Dry Run, with optional
• Invoke Lambda Stream: response-streaming functions delivered piece by piece (UTF-8 safe)
• Invoke Lambda Batch: one function, many payloads, parallel, results in order
• Send Signed Request: AWS SigV4 for API Gateway (IAM auth), Lambda function URLs and
• Amazon Cognito identity pools for guest and signed-in players (Set Login Token for any
• Static keys (development and servers) and the default AWS credential chain
• Function name prefix and default qualifier (alias) from the project settings
• Struct To JSON, JSON To Struct and Get JSON Field with path syntax such as
• Background worker threads, automatic retries with back-off, timeouts, custom endpoints
• Cancellable latent nodes; all results delivered on the game thread
• C++ API with a native callback

Blueprint & C++ API

Every call is reachable from more than one place — pick the entry point that fits your project:

Callable runs when executed · Pure no exec pin, returns a value · LatentAsync finishes later and fires its outputs

LambdaLink 2

Config 3

Identity 5

JSON 3

Events & delegates

Bind these in Blueprint (drag off the object → Bind Event) or with AddDynamic in C++.

Project settings

Configure once under Project Settings › Plugins › LambdaLink — values are saved to the project's config .ini, so they travel with the project and your build.

Options & enums

Compatibility

One ready-made build per engine version is included in the download — copy the one that matches your project.

Technical details

What's in the download

Quick start

1. Unzip the download and pick the build that matches your engine (4.27 · 5.8).
2. Copy the LambdaLink folder into your project's Plugins/ folder (create it if needed).
3. Open the project, enable LambdaLink under Edit › Plugins and restart the editor.
4. Fill in Project Settings › Plugins › LambdaLink.
5. Right-click in any Blueprint graph and search LambdaLink — or include the public headers from C++.
6. Package for your target platform (Windows, Linux, Android).

Good to know