Add a subtask to a task

Adds an existing task as a subtask to the specified parent task. Subtasks allow you to break down complex tasks into smaller, more manageable units with clear assignments and better tracking. Each subtask works like its own ticket with its own description, assignee, priority, and status. The parent task identifier can be either a UUID or a numeric shortNumber. The subtask must exist and be accessible to the user. Requires Tasks.editAnyTitleAndDescription permission.

POST/tasks/{identifier}/subtasks

Authorization

AuthorizationOAuth2 access token · headerrequired

Scopes:api:write

AuthorizationBearer token (JWT) · headerrequired

Path parameters

identifierstringrequired

Parent task UUID or numeric shortNumber

Query parameters

fieldsToReturnstring

Comma-separated list of top-level response fields to return. Overrides the endpoint compact default unless responseShape=full is used.

responseShapestring

Advanced override. Omit for the endpoint compact default. Use full only when you need the complete endpoint response, including nested fields that are not selectable with fieldsToReturn.

Allowed:compactfull

Header parameters

LT-Response-Shapestring

Advanced override. Set to full only when you need the complete endpoint response, including nested fields that are not selectable with fieldsToReturn.

Allowed:full

Request body

requiredapplication/json

subtaskIdstringrequired

UUID of an existing task to add as a subtask to the parent task. The subtask must exist in the workspace and be accessible to the user. The subtask will be linked to the parent task specified in the URL path.

Responses

200

Subtask added successfully

accountableobject

Accountable user details

accountableIdstring

Accountable user ID

assignedToobject

Assigned user details

assignedToIdstring

Assigned user ID

billedbooleanrequired

Whether task is billed

blockedByIdsstring[]required

Task IDs that currently block this task

blockingIdsstring[]required

Task IDs that this task currently blocks

childSpentTimenumberrequired

Child tasks spent time in minutes

commentsobject[]required

Task comments; each body is HTML and may contain the same embedded appImage / appFile / appVideo divs with fileId as the task description. Fetch binaries via authenticated /api/public/workspace/files/{fileId} with the same Public API Bearer token when needed.

componentItemIdobject

Component item ID

createdAtstring<date-time>required

Task creation timestamp

customFieldsobjectrequired

Custom fields values

deadlinestring<date-time>

Task deadline

descriptionstringrequired

Task description in HTML. May include embedded assets as elements such as <div data-type="appImage" fileId="…" filename="…"> (images), appFile, or appVideo—binary content is not embedded; use authenticated GET {appOrigin}/api/public/workspace/files/{fileId} with the same Public API Bearer token to retrieve it.

emailDetailsobject

Email details

emailSendErrorstring

Email send error message

emailSendErrorCodestring

Email send error code

emailSendFailedAtstring<date-time>

Email send failed timestamp

emailSendFailedTostring[]

Email send failed recipients

enableSupportContingentbooleanrequired

Enable support contingent

estimatedTimenumber

Estimated time in hours

guestAccessbooleanrequired

Guest access enabled for organization members

historyobject[]required

Task history entries

iconobject

Task icon identifier in the format :icon_name: (e.g., :rocket:, :bug:, :memo:). Can be null if no custom icon is set.

iconIsGeneratingbooleanrequired

Whether icon is being generated by AI

idstringrequired

Task ID (UUID)

isBlockedbooleanrequired

True when at least one blocker is still New, In progress, Feedback, or Backlog

isChangeRequestbooleanrequired

Whether task is a change request

isParticipantbooleanrequired

Whether current user is a participant

notificationSettingsobjectrequired

Notification settings

parentTaskIdobject

Parent task ID for subtasks

participantsCountnumberrequired

Number of participants

participantsListstring[]required

List of participant user IDs

priorityobjectrequired

Task priority (TaskPriority enum)

productsobject[]required

Task products

projectobjectrequired

Project information

projectIdstringrequired

Project ID

quotationsobject[]required

Express quotations

shortNumbernumberrequired

Task short number (workspace-scoped)

skipFromBillingboolean

Skip from billing

spentTimenumberrequired

Total spent time in minutes

statusIdstringrequired

Task status ID

subTasksIdsstring[]required

Child task IDs

summarystring

Task summary

summaryIsGeneratingbooleanrequired

Whether summary is being generated by AI

tagsstring[]required

Task tags

titlestringrequired

Task title

titleIsGeneratingbooleanrequired

Whether title is being generated by AI

typeIdstringrequired

Task type ID

userIdstringrequired

Creator user ID

400

Invalid identifier format or validation errors

401

Unauthorized - Invalid or missing authentication token

403

Access denied: No access to project or task not editable

404

Task not found

Try it

Server

Base URLCustom base URLOverrides the selected server when set.

Authorization

OAuth2 access tokenRemember on this deviceInclude my values in samples

Parameters

identifierpath*Parent task UUID or numeric shortNumberfieldsToReturnqueryComma-separated list of top-level response fields to return. Overrides the endpoint compact default unless responseShape=full is used.responseShapequeryAdvanced override. Omit for the endpoint compact default. Use full only when you need the complete endpoint response, including nested fields that are not selectable with fieldsToReturn.LT-Response-ShapeheaderAdvanced override. Set to full only when you need the complete endpoint response, including nested fields that are not selectable with fieldsToReturn.

Bodyapplication/json

subtaskIdstring*UUID of an existing task to add as a subtask to the parent task. The subtask must exist in the workspace and be accessible to the user. The subtask will be linked to the parent task specified in the URL path.

Request

curl -X POST "https://leadtime.app/api/public/tasks/550e8400-e29b-41d4-a716-446655440000%20or%20123/subtasks" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
  "subtaskId": "550e8400-e29b-41d4-a716-446655440000"
}'

const response = await fetch("https://leadtime.app/api/public/tasks/550e8400-e29b-41d4-a716-446655440000%20or%20123/subtasks", {
  method: "POST",
  headers: {
    "Authorization": "Bearer YOUR_ACCESS_TOKEN",
    "Content-Type": "application/json"
  },
  body: "{\n  \"subtaskId\": \"550e8400-e29b-41d4-a716-446655440000\"\n}"
});

import requests

response = requests.post(
    "https://leadtime.app/api/public/tasks/550e8400-e29b-41d4-a716-446655440000%20or%20123/subtasks",
    headers={
        "Authorization": "Bearer YOUR_ACCESS_TOKEN",
        "Content-Type": "application/json"
    },
    data="{\n  \"subtaskId\": \"550e8400-e29b-41d4-a716-446655440000\"\n}",
)

Response

{
  "accountable": {},
  "accountableId": "string",
  "assignedTo": {},
  "assignedToId": "string",
  "billed": true,
  "blockedByIds": [
    "string"
  ],
  "blockingIds": [
    "string"
  ],
  "childSpentTime": 0,
  "comments": [
    {}
  ],
  "componentItemId": {},
  "createdAt": "2019-08-24T14:15:22Z",
  "customFields": {},
  "deadline": "2019-08-24T14:15:22Z",
  "description": "string",
  "emailDetails": {},
  "emailSendError": "string",
  "emailSendErrorCode": "string",
  "emailSendFailedAt": "2019-08-24T14:15:22Z",
  "emailSendFailedTo": [
    "string"
  ],
  "enableSupportContingent": true,
  "estimatedTime": 0,
  "guestAccess": true,
  "history": [
    {}
  ],
  "icon": {},
  "iconIsGenerating": true,
  "id": "string",
  "isBlocked": true,
  "isChangeRequest": true,
  "isParticipant": true,
  "notificationSettings": {},
  "parentTaskId": {},
  "participantsCount": 0,
  "participantsList": [
    "string"
  ],
  "priority": {},
  "products": [
    {}
  ],
  "project": {},
  "projectId": "string",
  "quotations": [
    {}
  ],
  "shortNumber": 0,
  "skipFromBilling": true,
  "spentTime": 0,
  "statusId": "string",
  "subTasksIds": [
    "string"
  ],
  "summary": "string",
  "summaryIsGenerating": true,
  "tags": [
    "string"
  ],
  "title": "string",
  "titleIsGenerating": true,
  "typeId": "string",
  "userId": "string"
}