Quickstart

The Transactional API over HTTP needs three things: an account, an api_sms token and one POST request. This walkthrough takes you from zero to a delivered message. If you already know you need high throughput or API-driven campaigns, jump straight to Bulk sending — same token, one call, up to 100 messages per request.

1. 1

   Create an Instasent account

   Sign up at instasent.com and complete onboarding. A Transactional API token is issued automatically for your first project.

2. 2

   Grab your token

   In the dashboard, open API tokens and copy the api_sms token. Treat it as a secret — never commit it to version control.

3. 3

   Send your first message

   curlnodepython

   curl -X POST https://api.instasent.com/transactional/v1/sms \
     -H "Authorization: Bearer $INSTASENT_TOKEN" \
     -H "Content-Type: application/json" \
     -d '{
       "from": "Instasent",
       "to": "+34600000000",
       "text": "Hello from Instasent"
     }'

4. 4

   Check delivery

   The response contains an id. Point your webhook endpoint at the DLR URL in your project settings — Instasent will POST delivery updates as the message progresses through the carrier network. See Receiving DLRs for payload details.

Sending many messages at once

For API-driven campaigns, notification fan-outs or any high-volume dispatch, switch from POST /sms to POST /sms/bulk — a single call that carries up to 100 messages, returns accepted and rejected items side by side, and queues the accepted ones on the platform for fastest-possible dispatch. The same api_sms token works.

curl -X POST https://api.instasent.com/transactional/v1/sms/bulk \
  -H "Authorization: Bearer $INSTASENT_TOKEN" \
  -H "Content-Type: application/json" \
  -d '[
    { "from": "Instasent", "to": "+34600000001", "text": "Hello one" },
    { "from": "Instasent", "to": "+34600000002", "text": "Hello two" }
  ]'

Full request and response shape, per-request limits, throughput model and partial-success handling live in Bulk sending.

What's next

• Bulk sending — POST /sms/bulk, 100 messages per request, queue-based throughput. The endpoint to use for campaigns.
• Authentication — token scopes, rotation, header vs. query-string.
• Rate limits — per-endpoint limits and how to read the X-RateLimit-* headers. One bulk call counts as one request against the window.
• Errors — status codes, error payload shape, retry guidance.
• Receiving DLRs — webhook payload and status list.
• Reference — every endpoint, every parameter.