OpenAPI and AsyncAPI are powerful specification languages for REST and event-driven APIs. They're machine-readable and excellent for developers—but when designing APIs collaboratively, the YAML-based standards can overwhelm business stakeholders.

We developed the API Product Canvas to solve this problem: a visual tool that bridges Domain-Driven Design and API specifications. It captures a bounded context and shows both the APIs it provides and those it consumes, combining synchronous and asynchronous interfaces in a single view. For each API, the canvas visualizes aggregates, operations, events, and payloads in a format that IT and business experts can discuss together.

In this talk, we'll share our learnings from running API design workshops across industries. You'll see how the canvas guides teams through designing REST and event-driven APIs—making explicit decisions that often remain implicit until implementation. We'll also demonstrate how to accelerate the workflow by using AI to generate a first OpenAPI or AsyncAPI spec draft directly from the canvas.

You'll leave with a practical methodology for facilitating API design sessions that produce well-architected, business-oriented APIs that everyone involved understands.

Takeaways:
- The API Product Canvas as a visual facilitation tool for collaborative API design
- How to engage non-technical stakeholders in OpenAPI and AsyncAPI specification
- Using AI to generate first API spec drafts from canvas results