Create and version modals with the API

See availability for production and staging endpoints.

Create and version modals

modals:read and modals:write are available to members, admins and owners. Validate before saving:

POST /v1/modals/validate
Content-Type: application/json

{
  "title": "Review request",
  "submit_label": "Submit",
  "close_label": "Cancel",
  "blocks": [
    {
      "type": "input",
      "label": { "type": "plain_text", "text": "Reason for {{request}}" },
      "element": { "type": "plain_text_input", "action_id": "reason", "multiline": true }
    }
  ],
  "sample_data": { "request": "this change" }
}

Validation returns normalized blocks, the builder-compatible placeholder_mapping, and a compiled_view. It uses the same compiler as slack-modal-open, calls no external service and spends no credits. For creation, add name and POST the same content to /v1/modals, optionally with activate: true. Definition and first version commit together or neither exists. The default is a current draft version, so the web editor can load it. Current does not mean active: activate it before referencing it from an interactive button; a foreign, draft, inactive or missing modal is rejected during template authoring.

GET /v1/modals lists definitions; GET /v1/modals/{id} includes the current version.
PATCH /v1/modals/{id} edits name, description, title and labels; omitted fields stay unchanged.
GET /v1/modals/{id}/versions lists newest first.
POST /v1/modals/{id}/versions appends blocks, sample_data, and optional activate.
POST /v1/modals/{id}/versions/{version_id}/activate atomically selects an existing version.

Block content is versioned. Creating another API draft leaves the existing active version selected. Saving a draft in the browser makes that modal unavailable to opening until it is active again. Check the selected version and status before connecting a button. Supported authoring blocks are input, section, context and divider, with existing modal directive containers. Supported inputs are plain-text, static select, checkboxes, radio buttons, date and time pickers. Title/labels allow 24 characters; compiled views allow at most 100 blocks, following Slack’s view contract. The modal compiler’s if directive tests a truthy dot path; it does not support the message compiler’s operator conditions or elseChildren. Validate representative sample data for every branch. Dynamic data can still produce an invalid Slack view later; local validation does not call Slack. There is no API endpoint to open a modal independently of a Slack interaction. Test by sending a message with an Open Modal button. See Data binding and Submissions to complete the workflow.

Contracts and permissions

Interactive APIs (preview)

API endpoints

Create and version modals with the API

Create and version modals

​Create and version modals

Create and version modals