> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lithoblocks.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Modal submissions

> Process modal form submissions — send webhooks with form data and update messages after submission.

When users submit a modal, you can send the form data to your backend and/or update the original Slack message. Use this for feedback, approvals with comments, and data entry workflows.

## Prerequisites

* Understanding of [Modal basics](/guides/modals-basics)
* Familiarity with [Button webhooks](/guides/button-webhooks)
* Knowledge of [Message updates](/guides/button-message-updates)

## Submission flow

1. User fills the modal and clicks **Submit**
2. LithoBlocks receives the submission and extracts form values
3. You can trigger a **webhook** (POST form data to your API) and/or a **message update** (change the original message)
4. Optional: show a confirmation or thank-you in the message

## Submission data

Form values are sent as a structured object, for example:

```json theme={null}
{
  "field_label_1": "value",
  "field_label_2": ["option1", "option2"],
  "field_label_3": "2024-12-25"
}
```

Field keys match your modal field labels or IDs; values are strings, arrays (multi-select), or formatted dates/times.

## Configure submission actions

1. Open your modal definition
2. Under **On submit**, add one or both:
   * **Webhook** — Select a webhook destination; the payload will include the form data (and optional interaction placeholders)
   * **Message update** — Choose strategy (replace self, replace all, add response block) and define the new content
3. Save the modal

## Combined actions

You can run both a webhook and a message update on submit: e.g. POST data to your API and append "✓ Submitted by \[user] at \[time]" to the original message.

## Webhook usage in templates

Modal submission webhooks use the same **webhook destinations** as buttons. For advanced configuration — authentication, retries, payload templating, and monitoring — see [Webhook destinations](/guides/webhook-destinations). To view and debug webhook delivery and responses, see [Understanding logs](/guides/logs).

## Next steps

<CardGroup cols={2}>
  <Card title="Modal basics" icon="window-maximize" href="/guides/modals-basics">
    Create and configure modals.
  </Card>

  <Card title="Webhook destinations" icon="link" href="/guides/webhook-destinations">
    Auth, retries, and advanced payload config.
  </Card>

  <Card title="Understanding logs" icon="list" href="/guides/logs">
    Debug webhook delivery and responses.
  </Card>
</CardGroup>