How to Design a REST API in Anypoint Code Builder (OpenAPI + VS Code + Exchange) (Part 1)

In this step-by-step tutorial, you’ll learn how to design a complete REST API in Anypoint Code Builder using OpenAPI 3.0, right inside VS Code — no XML, flows, or Studio required.

We’ll cover everything from defining your endpoints and data models, to testing with mock responses and publishing your spec to Anypoint Exchange.

✅ What you'll learn:

Create an API spec using OpenAPI 3.0 YAML in ACB
Define all RESTful endpoints for /tasks and /tasks/{taskId}
Add reusable schemas with Task and TaskInput models
Test your API using the built-in mock console
Publish to Anypoint Exchange for sharing and scaffolding later

Whether you're new to MuleSoft or transitioning from Anypoint Studio, this is the API-first workflow you’ll want to master.

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Chapters:
00:00 Intro – What We're Building
00:20 Start a New OpenAPI Spec Project in ACB
01:13 Fill Out the API Info Block (Title, Version, Description)
01:35 Define the /tasks Endpoint: GET All & POST New Tasks
04:11 Define the /tasks/{taskId} Endpoint: GET, PUT, DELETE by ID
06:31 Create the Task and TaskInput Data Models
09:29 Test the API with the Built-in Mock Console
12:55 Quick Note on API Governance (Optional)
13:11 Publish Your API Spec to Anypoint Exchange
15:03 Final Thoughts & What’s Coming Next