Custom Action Builder UI for Workflow Actions!

What is it?

The Custom Action Builder is a visual, guided tool that gives app partners and developers a dedicated UI for creating custom workflow actions—no need to rely solely on the API.

Instead of hand-writing JSON, you can:

• Quickly configure inputs, outputs, and dependencies through an intuitive UI.
• Preview actions in-app to see exactly how they’ll appear to users.
• Generate ready-to-use JSON automatically, eliminating repetitive manual work.

This makes building custom actions faster, easier, and less error-prone, so you can focus on delivering valuable functionality instead of troubleshooting setup.

Why does it matter?

HubSpot provides a variety of tools for external developers to extend the platform—such as CRM cards, timeline events, and webhooks. Until now, there’s been no dedicated UI for configuring custom automation actions.

Previously, developers were limited by relying only on our Custom Workflow Action API to create actions. This meant hand-writing JSON definitions and relying heavily on documentation examples to get the structure right.

As a result, many developers expressed frustration with the lack of a UI—spending extra time setting up and troubleshooting actions. Without a clear way to configure and preview actions, the process was inefficient and prone to errors.

The Custom Action Builder:

• Speeds up development: define and preview your action in minutes versus hours or days.
• Reduces errors: guided setup ensures your JSON is valid and in the correct format for publishing.
• Provides a preview: see how your action will appear in Workflows before deploying.
• Eliminates repetitive work: copy and paste the generated JSON instead of hand-crafting it.

This means developers can finally focus on building valuable functionality for customers, not spending time wrestling with syntax or debugging errors.

How does it work?

From your developer account, open your app and launch the Custom Workflow Action Builder. In the UI, you can configure inputs, action details, and API requests, then preview how the action will appear in HubSpot Workflows. When you’re ready, copy the generated JSON and use it with HubSpot’s Custom Action API or on the new Project's Framework!

Who gets it?

Available to users on the new HubSpot Developer Platform or in existing Developer Test Accounts.

Learn More:

Learn more on the Knowledge Base