> ## Documentation Index
> Fetch the complete documentation index at: https://developers.cutshort.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Send a follow-up message in a thread

> Sends a reply in an EXISTING conversation thread (candidates already in the job pipeline). Get threadId from GET /jobs/{jobId}/applications or from the invite-to-apply response when present. This is NOT first-contact outreach — use POST /invite-to-apply for search candidates not yet in the pipeline.

Requires scope `messages:write` (production keys). Does not consume the invite-to-apply messages quota. Rate limit: global 120 requests per 60s per API key.



## OpenAPI

````yaml /openapi/public-api-v1.json post /messages
openapi: 3.1.0
info:
  title: Cutshort Public API v1
  version: 1.0.0
  description: >-
    Programmatic access to Cutshort's tech talent database. All endpoints
    require `Authorization: Bearer cs_live_<key>`.


    **Core flow:** search candidates → get candidate details (auto-unlock) →
    post a job → invite to apply (first contact) → list applications → send
    message (in-thread follow-up).
servers:
  - url: https://cutshort.io/api/v1
    description: Production
security:
  - ApiKeyAuth: []
tags:
  - name: Search
    description: Talent database search
  - name: Candidates
    description: Candidate detail with auto-unlock (contact info + resume)
  - name: Jobs
    description: Job posting and listing
  - name: Outreach
    description: >-
      Candidate outreach: first-contact invite to apply, and in-thread follow-up
      messages
  - name: Usage
    description: Cycle usage meters and quotas
  - name: Stages
    description: Job pipeline stages and counts
  - name: Applications
    description: List applications and move them between pipeline stages
paths:
  /messages:
    post:
      tags:
        - Outreach
      summary: Send a follow-up message in a thread
      description: >-
        Sends a reply in an EXISTING conversation thread (candidates already in
        the job pipeline). Get threadId from GET /jobs/{jobId}/applications or
        from the invite-to-apply response when present. This is NOT
        first-contact outreach — use POST /invite-to-apply for search candidates
        not yet in the pipeline.


        Requires scope `messages:write` (production keys). Does not consume the
        invite-to-apply messages quota. Rate limit: global 120 requests per 60s
        per API key.
      operationId: sendMessage
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - threadId
                - message
              properties:
                threadId:
                  type: string
                  description: Conversation thread ID from list applications
                message:
                  type: string
                  description: Follow-up message text
      responses:
        '200':
          description: Message sent
          content:
            application/json:
              schema:
                type: object
                properties:
                  success:
                    type: boolean
                  threadId:
                    type: string
                  messageId:
                    type: string
                    nullable: true
                    description: Upstream message / thread identifier when returned
        '400':
          description: Upstream send failed (error_code send_message_failed)
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ApiError'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '403':
          $ref: '#/components/responses/Forbidden'
        '404':
          $ref: '#/components/responses/NotFound'
components:
  schemas:
    ApiError:
      type: object
      properties:
        error_code:
          type: string
        error_description:
          type: string
  responses:
    Unauthorized:
      description: Missing or invalid API key
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ApiError'
    Forbidden:
      description: Insufficient scope (e.g. eval key calling a production-only endpoint)
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ApiError'
    NotFound:
      description: Resource not found
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ApiError'
  securitySchemes:
    ApiKeyAuth:
      type: http
      scheme: bearer
      description: >-
        Workspace-scoped API key. Prefix: `cs_live_`. Eval keys (self-serve from
        Cutshort → Settings → Integrations → API Key) can search and get
        candidate details within small quotas; production keys add job posting
        and candidate messaging with higher limits.

````