As serverless applications grow, APIs rarely live in a single project for long.

Teams break functionality into focused Lambda Annotation projects, deploy them independently, and often place them behind a single API Gateway. The architecture scales beautifully—but documentation doesn’t always keep up.

With LambdaOpenApi 1.1.0, we’re introducing a new capability designed specifically for this reality: the OpenAPI Schema Merge Tool.

The Problem We Kept Running Into

LambdaOpenApi has always focused on producing accurate, compile-time OpenAPI specifications directly from your Lambda code. That works extremely well—right up until you have:

• Multiple Lambda Annotation projects
• One shared API Gateway
• A desire for one authoritative API definition

What you end up with is a collection of perfectly valid OpenAPI specs… and no clean way to present them as a single platform API.

This friction shows up everywhere:

• Documentation portals feel fragmented
• SDK generation becomes awkward
• Gateway-level validation and tooling expect one spec, not many

Introducing the OpenAPI Merge Tool

LambdaOpenApi 1.1.0 adds a first-class solution to this problem.

The new OpenAPI Merge Tool allows you to combine multiple OpenAPI specifications into one unified definition, while preserving the boundaries and intent of each underlying service.

It’s designed for teams that:

• Implement APIs across multiple Lambda Annotation projects
• Deploy those APIs behind a shared API Gateway
• Want a clean, consolidated OpenAPI document for docs, tooling, or governance

Most importantly, it does this without forcing you to change how you structure or deploy your services.

Designed for Real-World Serverless Architectures

This release isn’t about squeezing everything back into a monolith.

The merge tool respects the reality of modern serverless systems:

• Independent services
• Independent deployments
• Shared infrastructure at the edge

You can namespace APIs, keep schemas distinct, and still present a cohesive platform surface—something that’s historically been painful to achieve without custom scripts or fragile build steps.

A Natural Extension of LambdaOpenApi

LambdaOpenApi has always been opinionated about one thing: your OpenAPI spec should reflect your code, not drift from it.

The merge tool extends that philosophy one step further:

• Generate specs at compile time
• Merge them intentionally
• Publish a single source of truth

No hand-edited mega-specs. No guesswork. No duct tape.

What This Means Going Forward

LambdaOpenApi 1.1.0 lays the groundwork for:

Better platform-level documentation

• Cleaner API Gateway configurations
• Easier client and SDK generation
• More confidence as systems scale

If you’re already using LambdaOpenApi across multiple services, this release is designed to fit directly into your existing workflow.

📖 Learn more and get started:

Check out the full documentation for the OpenAPI Merge Tool to see how it fits into your architecture.