How to send your first SMS via API in 5 minutes – the complete guide

Create an account on the sign-up page – you get 100 free SMS, no credit card and no contract. Activation is instant, so you are not waiting on sales approval. In the client panel you generate and download a Bearer Token (the token can also be obtained through customer support). Treat it like a password – keep it in environment variables (e.g. ACTIO_TOKEN), never in a repository or front-end code. If it leaks, revoke it in the panel and generate a new one; the old one stops working immediately.

The fastest test is a single call from the terminal. The endpoint accepts JSON and returns a message ID and status:

curl -X POST https://api.sendly.link/api/sms \
  -H "Authorization: Bearer $ACTIO_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "to": "48732129000",
    "body": "Your login code: 482910"
  }'

Two fields do the work: to (recipient number, 9–11 digits) and body (message content). The full reference – including the optional from field – is in the documentation.

The API is plain REST, so it works with any language that speaks HTTP – no closed libraries to install. In Node.js the built-in fetch is enough; in Python use requests.post(...), in PHP cURL, in Go the standard net/http. Ready snippets in five languages are in the documentation – copy, swap the token, done.

Sending an SMS is only half the story – you want to know it arrived. Sendly does not push statuses on its own: in the panel (SMS Gateway → Service settings) you enable deliveries and enter a public URL. Both steps are required. Then, instead of polling the API, you get a POST application/json (up to 36 attempts from the IP of api.sendly.link; 200 OK stops retries, as do 404 and 418). Two types: NOTIFICATION (send status – message_id and status: DELIVERED or ERROR) and MESSAGE (inbound SMS – from, to, body). Store message_id from the API response so you can match the callback to that message. Details and checklist: SMS API docs.

In production, handle the API status codes up front. Success is 200 – the message is accepted for sending and the response contains a message_id. Errors: 403 (authorization problem), 422 (validation error – details in the errors.token / errors.to / errors.body fields) and 429 (rate limit exceeded). A good integration logs the message_id and status, and on 429 applies exponential backoff.

The same API covers three very different scenarios without changing the integration: transactional notifications, 2FA / OTP codes and bulk campaigns to thousands of recipients. Billing is pay-as-you-go, with no subscription or entry threshold – check the rate for your volume in the pricing.