---
title: "Send a signal to an workflow"
method: POST
path: "/workflow/{id}/signal/{signal}"
---

# Send a signal to an workflow

`POST /workflow/{id}/signal/{signal}`

## Request

- Base URL: `http://localhost:3001`
- URL: `http://localhost:3001/workflow/{id}/signal/{signal}`
- Auth: none required
- TypeScript: <https://skmtc.dev/growthxai/apis/output-ai-api/docs/workflow/:id/signal/:signal/post.ts> (a function with typed inputs; its response is checked against the schema)

Always targets the latest run; `runId` cannot be pinned for Temporal signal operations.

## Path parameters

- `id` string, required
- `signal` string, required

## Request body

- object
  - `payload` object: The payload sent to the signal operation

## Response `200`

Success

## Other responses

- `400`: Invalid request body, query, or pagination token
- `404`: Workflow execution, workflow type, or catalog not found
- `500`: Internal server error (e.g. Temporal connection failure)

## Changes

- **2026-04-24** `01552bfa9579`: 2 breaking, 3 warning
  - added `#/components/schemas/ValidationErrorResponse, #/components/schemas/ErrorResponse` to the response body `oneOf` list for the response status `400`
  - the response's body type changed from `object` to no type for status `400`
  - removed the optional property `error` from the response with the `400` status
  - removed the optional property `issues` from the response with the `400` status
  - …1 more
- **2026-03-13** `0f0e49049ef1`: 1 breaking, 4 info
  - the response's body type changed from no type to `object` for status `400`
  - removed `#/components/schemas/ValidationErrorResponse, #/components/schemas/ErrorResponse` from the response body `oneOf` list for the response status `400`
  - added the optional property `error` to the response with the `400` status
  - added the optional property `issues` to the response with the `400` status
  - …1 more

[Operation history](https://skmtc.dev/growthxai/apis/output-ai-api/changes/workflow/:id/signal/:signal/post.md)

---

[API](https://skmtc.dev/growthxai/apis/output-ai-api.md) - [All operations](https://skmtc.dev/growthxai/apis/output-ai-api/llms.txt) - [OpenAPI document](https://skmtc.dev/growthxai/apis/output-ai-api/revisions/d34370cdff2d?raw)