Developer documentation · Last checked: September 2026
The LemTask task API
A small REST surface for the thing people automate most: tasks. Read your list, add items from a script, mark them done, remove them. Paid accounts only, authenticated with the account key already in your settings.
Base URL
$LEMTASK_API_BASE/api-tasksSign in and open Settings → Quick Capture Methods to see the exact base URL and your key. The examples below use $LEMTASK_API_BASE as a placeholder — set it once in your shell and paste the commands as they are.
Send your key as an X-API-Key header, or a signed-in session token as Authorization: Bearer …. Responses are JSON: successful reads return { data, meta }, writes return { data }, failures return { error, message }.
Endpoints
GET /api-tasks
List your tasks. Optional filters: completed=true|false, priority, list_id, due_date (YYYY-MM-DD), limit (max 200, default 50), offset.
curl "$LEMTASK_API_BASE/api-tasks?completed=false&limit=20" \
-H "X-API-Key: YOUR_KEY"POST /api-tasks
Create a task. title is required (max 500 characters). Optional: notes, due_date, due_time, priority (0-3), list_id, duration_minutes. Returns 201 with the created task.
curl -X POST "$LEMTASK_API_BASE/api-tasks" \
-H "X-API-Key: YOUR_KEY" \
-H "Content-Type: application/json" \
-d '{"title":"Send the invoice","due_date":"2026-09-30","priority":1}'PUT /api-tasks?id={task_id}
Update a task. Send only the fields you want changed. Setting completed:true stamps the completion time; setting it false clears it.
curl -X PUT "$LEMTASK_API_BASE/api-tasks?id=TASK_ID" \
-H "X-API-Key: YOUR_KEY" \
-H "Content-Type: application/json" \
-d '{"completed":true}'DELETE /api-tasks?id={task_id}
Delete a task. This is a soft delete, so the task moves to your trash and can be restored in the app.
curl -X DELETE "$LEMTASK_API_BASE/api-tasks?id=TASK_ID" \
-H "X-API-Key: YOUR_KEY"Getting your key
- Sign in to LemTask and open Settings.
- Find Quick Capture Methods and copy the 16-character key.
- Send it as an
X-API-Keyheader on every request. - Keep it out of anything public — front-end code, shared repositories, screenshots. It reads and writes your tasks.
Errors you should expect
- 401 — no valid key or session token was supplied.
- 403 — the account is on the free plan. API access needs Pro or Teams.
- 400 — a missing task id on update or delete, an empty title, or a title over 500 characters.
- 404 — the task id does not belong to this account.
What is not covered yet
Tasks only. Habits, notes, journal entries, focus sessions and team data have no public endpoints. There is also no Model Context Protocol server, so assistants cannot connect to LemTask by pasting a link — if that is what you are after, see which task apps do have an MCP server. Until ours ships, the practical routes are a custom GPT action pointed at the endpoints above, your own Claude tool definition, or Zapier, Make and Apple Shortcuts calling the same URLs.
Questions
Want to try it?
Every new account starts on a Pro trial, so you can create a key and make your first API call in a couple of minutes.