Short answer
Custom code actions run Node.js by default. Properties come in through event.inputFields, and callback({ outputFields }) returns values that later actions can use, for example with Edit record. Keep tokens in secrets. HubSpot's docs say that to have a rate-limited call retried, you must throw the error in your catch block. Logs are in the workflow's action logs.
1. Where it is
2. The shape of the code
exports.main = async (event, callback) => {
const email = event.inputFields['email'];
try {
// call another system here
callback({ outputFields: { domain: email.split('@')[1] } });
} catch (err) {
// throw so HubSpot retries rate-limited calls
throw err;
}
};3. Practical notes
- Inputs and outputs are typed fields in the action panel. Declare outputs so other actions can see them.
- Swallowing errors means no retry and a silent success.
- Agent Hub workflows also support custom code. See agentic workflows.