Send a message - Cutshort API

Requires a production key with the messages:write scope. To upgrade from eval access, email hello@cutshort.io. For API support, email engineering@cutshort.io from your Cutshort account email.

POST /messages sends a follow-up reply in an existing Cutshort conversation thread — for candidates who are already in your job pipeline (for example in Applications after an invite or apply).

When to use this vs invite to apply

	`POST /invite-to-apply`	`POST /messages` (this guide)
Use for	First contact from search / talent database	Follow-up in an existing thread
Needs	`talentCardId` + `jobId` + `message`	`threadId` + `message`
If already in pipeline	409 `already_exists_in_job_pipeline`	Send here instead
Quota	Counts against workspace `messages` meter	Not counted on the invite quota (still needs `messages:write`)

Get threadId from List applications (each application row may include threadId), or from the invite response when present.

Request

POST /api/v1/messages

{
  "threadId": "64f1a2b3c4d5e6f7a8b9c0d3",
  "message": "Thanks for applying — are you free for a 20-min intro this week? https://cal.com/acme/intro"
}

Field	Required	Notes
`threadId`	Yes	Conversation thread for this job ↔ candidate
`message`	Yes	Plain text reply

Response

{
  "success": true,
  "threadId": "64f1a2b3c4d5e6f7a8b9c0d3",
  "messageId": "…"
}

Typical flow

Invite to apply for first contact
List applications to find candidates in Applications and their threadId
Send a personalized follow-up with POST /messages

curl -s -X POST "https://cutshort.io/api/v1/messages" \
  -H "Authorization: Bearer cs_live_PROD_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "threadId": "THREAD_ID",
    "message": "Thanks for applying — happy to chat this week…"
  }'

Errors

`error_code`	HTTP	Meaning
`insufficient_scope`	403	Key lacks `messages:write` (eval keys cannot send)
`thread_not_in_workspace`	404	Unknown thread or not in your workspace
`send_message_failed`	400	Upstream send failed — safe to retry once