1
Create the form
Open Modals, create a modal, and set its internal name, user-visible title, submit label, and close label. Titles and button labels allow up to 24 characters.
2
Add inputs
Add an Input block for each field. Give every input a stable, unique
action_id, a clear label, and required/optional behavior. A multiline text area is a plain_text_input with multiline: true.3
Save and activate
Preview with representative data, save, and select the active version. A current draft is not an active modal; an inactive modal cannot be referenced by a new interactive template.
4
Connect a button
In a message template’s button actions, select Open Modal, choose the active modal, and configure data bindings. Configure the submission action as described in Modal submissions.
5
Test in Slack
Save and send the template to a test channel. Open the modal, check prefilled values, test required-field behavior, submit, and inspect interaction history and your receiver.
Input types
These are the supported inputs in the current modal authoring contract. Do not assume every Slack input type is accepted by LithoBlocks.
The API authoring path supports Input, Section, Context, Divider, and modal directive containers. Views allow at most 100 compiled blocks. Modal
if directives use truthy paths, not the message compiler’s full operator/else behavior.
See Modal API authoring for complete request bodies and Limits for validation guidance.