LinkedIn API endpoint

LinkedIn InMail API: reach beyond the network

Swarmhit's LinkedIn InMail API sends an InMail from a premium sender to a profile it is not connected to, with one POST to /accounts/{id}/inmails and an optional subject. Through Swarmhit, Sales Navigator and Recruiter senders reach open profiles without spending credits, within a plan-dependent allowance, and other sends draw the sender's InMail credits. Errors say exactly why a send could not go out.

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Endpoints

POST/accounts/{id}/inmails
Send an InMail
GET/accounts/{id}/connections/{identifier}
Check whether the profile is open

POST

/accounts/{id}/inmails

api/v1

curl -X POST https://app.swarmhit.com/api/v1/accounts/acc_123/inmails \
  -H "Authorization: Bearer $SWARMHIT_API_KEY" \
  -H "Idempotency-Key: 6f1c2f3e-inmail-ana" \
  -H "Content-Type: application/json" \
  -d '{
    "profileUrl": "https://www.linkedin.com/in/ana-lopez",
    "subject": "Your outbound stack",
    "text": "Hi Ana, a quick idea on scaling LinkedIn outreach across your team."
  }'

How the LinkedIn InMail API works

InMail needs a premium LinkedIn plan on the sender; free accounts cannot send any. The account resource shows the remaining balance as inmailCredits.
Through Swarmhit, Sales Navigator and Recruiter senders can InMail open profiles without spending credits, within a monthly allowance that depends on the plan. The connection check reports openProfile before you send.
Failures are explicit: 409 sender_paused, 409 inmail_not_available when the sender has no premium InMail access, and 429 inmail_credits_exhausted when the balance is empty.

As a campaign step

The same action runs inside sequences as the inmail step: one POST /campaigns sets up the whole sequence, and the engine schedules each step per sender and mailbox, inside the sending window, with rotation across senders.

The inmail step takes subject, text and their fallbacks, up to five variants each with its own attachments (voice notes belong to message steps), and ends on a reply.
whenUnable decides what happens when an InMail cannot be sent: auto pauses the sender when it is out of credits and otherwise moves on, pause always pauses the sender, skip always continues. Put an if_open_profile branch in front to spend credits only where they are needed.

Limits and safety

Each send counts against the sender's daily InMail cap, and the API answers 429 with details { limit, used, scope, resetAt } when it is reached.
Credit exhaustion is its own 429 code, inmail_credits_exhausted, so your product can tell a busy day from an empty balance.
Every sender runs on its own dedicated proxy with managed warmup and health checks, behind 250+ safeguards monitored 24/7.

LinkedIn senders cost $16.90 a month each for the first 50, tiered down to $6.90, with no minimum. See pricing.

Webhooks

Events to subscribe to: message.sent, message.received. Deliveries are signed and retried. How LinkedIn webhooks work

Going deeper: LinkedIn InMail guide.

LinkedIn InMail API, answered

Does the LinkedIn InMail API need Sales Navigator?

It needs a premium LinkedIn plan on the sender: Premium, Sales Navigator or Recruiter. Free accounts cannot send InMail. Through Swarmhit, Sales Navigator and Recruiter senders can also InMail open profiles without spending credits, within a monthly allowance that depends on the plan.

What happens when a sender runs out of InMail credits?

A direct send returns 429 with the code inmail_credits_exhausted. In a campaign, the inmail step's whenUnable setting decides: pause the sender, skip to the next step, or the default auto mode, which pauses the sender only when credits are gone.

What is an open profile on LinkedIn?

A premium member who accepts InMails from anyone on LinkedIn, without a connection. Through Swarmhit, Sales Navigator and Recruiter senders reach open profiles without using credits, within a plan-dependent allowance. The connection check returns an openProfile flag, and campaigns can branch on it with the if_open_profile step.

Can I send an InMail to a 1st-degree connection?

There is no need: connections receive regular messages, which cost no credits. Campaigns enforce it, since invite, inmail and connection checks cannot sit below a branch where the lead is already connected.