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A bulk SMS API that doesn't make you open a sales ticket

Grab an API key, send your first message in the next five minutes. Single sends, bulk queues of up to 500 messages per call, OTP verification, incoming messages and webhooks, all over plain REST with JSON. Route messages through your own Android phone for free, or through cloud gateways from €0.02 per SMS.

Your first message

One POST request. The queue handles retries, delivery tracking and channel routing.

# Send a single SMS curl -X POST "https://app.rcszilla.com/api/" \ -H "Authorization: Bearer YOUR_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "action": "send", "channel": "sms", "to": "+15551234567", "message": "Your order #1042 has shipped." }'
# Bulk: queue up to 500 messages in one call curl -X POST "https://app.rcszilla.com/api/" \ -H "Authorization: Bearer YOUR_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "action": "queue_bulk", "channel": "sms", "messages": [ {"to": "+15551234567", "message": "Hi Anna, your table is confirmed for 19:00."}, {"to": "+15559876543", "message": "Hi Mark, your table is confirmed for 20:30."} ] }'

Exact endpoints, parameters and response schemas (including OTP, incoming messages, webhooks and error codes) are in the API documentation, with examples in 9 languages.

What the API covers

Send anything

SMS, WhatsApp and email through one interface. Pick the channel per message.

Bulk queueing

Up to 500 messages per request, dispatched from a managed queue with per-message status.

OTP built in

Send and verify one-time passcodes without writing your own code store or expiry logic.

Incoming messages

Read replies received on your device, or get them pushed to your server by webhook.

Smart routing

Cloud messages automatically take the cheapest available gateway for each destination.

Device channel

Point the API at your own Android SMS gateway and pay nothing per message.

Developer questions

How much does the API cost?

The API is included with every account. Device sending is free per message; cloud sending starts at €0.02 per SMS, pay as you go, no monthly fee. Live per-country prices are on the pricing page.

Is there a sandbox?

Every account starts free. Pair your own phone as the sending device and test the full API against a real number without buying anything.

What about rate limits?

Bulk requests take up to 500 messages each; the queue dispatches at a sustainable rate for your channel. If you have a burst-heavy use case, tell support what you need; replies come within 24 hours.

Which languages have examples?

The docs show cURL and language-specific examples, and the reference is published in English, Romanian, German, French, Ukrainian, Bulgarian, Portuguese, Spanish and Turkish.

Get a key and start sending

Create a free account, copy your API key from the dashboard, and your first SMS is one curl away.

Get your API key

Stop sending messages one by one.

RCSZilla lets you send SMS, WhatsApp, and Email campaigns to thousands of contacts, all from one dashboard. Sign up free, no card required.