# Custom Workflow Actions: POST\_ACTION\_EXECUTION function

**URL:** <https://community.hubspot.com/t/custom-workflow-actions-post-action-execution-function/151429>\
**Category:** Develop, Build & Integrate\
**Tags:** workflow-extension\
**Created:** [June 25, 2026, 9:22pm UTC](https://community.hubspot.com/t/custom-workflow-actions-post-action-execution-function/151429 "2026-06-25T21:22:38Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![CHarro](https://avatars.discourse-cdn.com/v4/letter/c/dec6dc/32.png) [@CHarro](https://community.hubspot.com/u/CHarro)\
**Post date:** [June 25, 2026, 9:22pm UTC](https://community.hubspot.com/t/custom-workflow-actions-post-action-execution-function/151429/1 "2026-06-25T21:22:38Z")

</div>

I’m working on a custom workflow action, and cannot find documentation on the POST\_ACTION\_EXECUTION function type.

There is documentation about PRE\_ACTION\_EXECUTION, PRE\_FETCH\_OPTIONS, and POST\_FETCH\_OPTIONS functions [here](https://developers.hubspot.com/docs/api-reference/latest/automation/workflow-actions/custom-action-reference), and POST\_ACTION\_EXECUTION appears as a valid enum in the APIs (for instance [here](https://developers.hubspot.com/docs/api-reference/latest/automation/workflow-actions/functions/add-function)), but neither Claude nor I could find documentation on the event and callback shape.

I want to know what data is included in the event and required in the callback so that I can write my function accordingly.

Thanks!

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<div class="post-metadata">

**Author:** ![stassey](https://d10pqhm3lwygmk.cloudfront.net/user_avatar/community.hubspot.com/stassey/32/36_2.png) [@stassey](https://community.hubspot.com/u/stassey)\
**Post date:** [June 25, 2026, 9:41pm UTC](https://community.hubspot.com/t/custom-workflow-actions-post-action-execution-function/151429/3 "2026-06-25T21:41:56Z")

</div>

Hey @CHarro,

Thanks for bringing this to the community!

If you find this may be missing from our documentation, for future reference you can submit this feedback via the **[Developer Feedback form](https://developers.hubspot.com/feedback)**!

In the meantime, I’d like to tag in some of our Top Contributors to see if they have any tips and tricks on this!

Hey @evaldas, @Anton, @GRajput – Do you have any suggestions for @CHarro on this?

Sam, Community Manager

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<div class="post-metadata">

**Author:** ![MichaelMa](https://avatars.discourse-cdn.com/v4/letter/m/b5ac83/32.png) [@MichaelMa](https://community.hubspot.com/u/MichaelMa)\
**Post date:** [June 26, 2026, 12:17pm UTC](https://community.hubspot.com/t/custom-workflow-actions-post-action-execution-function/151429/4 "2026-06-26T12:17:44Z")

</div>

Indeed, there doesn’t look to be much documentation but I did find a Github that used it:

> **[GitHub - ballerina-platform/module-ballerinax-hubspot.automation.actions: This Ballerina connector provides capabilities to...](https://github.com/ballerina-platform/module-ballerinax-hubspot.automation.actions)**
>
> This Ballerina connector provides capabilities to integrate with HubSpot Automation API.

```auto
actions:PublicActionFunction publicActionFunction = {
    functionSource: "exports.main = (event, callback) => {\r\n callback({\r\n outputFields: {\r\n myOutput: \"example output value\"\r\n }\r\n });\r\n}",
    functionType: "POST_ACTION_EXECUTION"
};

```

This post also has an example:

> [@Custom Workflow Action is not able to use outputFields in workflow](https://community.hubspot.com/t/custom-workflow-action-is-not-able-to-use-outputfields-in-workflow/131054/8):
>
> Would you mind sharing your updated block of json? I’m actively building out my first workflow actions like this and the reference would be great!