Developer-Friendly HTTP SMS API with Global Reach
HTTP SMS
In order to automate the process of sending messages, businesses need to have an SMS API connection. It is especially helpful while sending Promotional messages, one time passwords, verification codes, and so on. HTTP SMS API, which can also be referred to as HTTP SMS, is the connection protocol used in message API integration.
SMS API supports HTTP. You can integrate an SMS HTTP API into your platform to send automated messages directly from your end without relying on third-party software. Full API reference (endpoints, parameters, sample requests) is available for developers.
Send99 is a tested and fully-scalable SMS API service provider that offers integration of functional HTTP SMS API. For all our partners who’d like to make use of this service, It is possible to automate the process of sending text messages directly from their platforms, who would like to make use of the service.
Our focus
Send99 aims to build a better future where technology creates good connections and communication for everyone and everywhere.
How the HTTP SMS API works
The Send99 HTTP SMS API lets your application submit messages without using the web portal. You send an HTTP GET or POST request with your account credentials, one or more destination numbers, and the message content. The gateway returns a JSON response containing a status code and per-recipient message IDs that you can store for reconciliation.
This is a good fit for OTPs, password resets, order updates, appointment reminders, and any workflow where the message is triggered by an event in your own system. It is also the simplest way to add SMS to a small application before moving to a higher-throughput protocol later.
Endpoints for balance, sending, and reports
The documented endpoints cover four jobs: checking the account balance, sending one or more messages, retrieving delivery reports for submitted message IDs, and retrieving inbound messages. The API documentation lists the parameters, sample requests, and JSON responses for each call, including optional fields such as sender, scheduled send time, and MMS title.
Store the returned message IDs. They are the key to matching a send with its delivery report and to answering customer-support questions later. If you send in batches, keep the mapping between your internal order or user ID and the gateway message ID.
Delivery reports and message status
Delivery reports show whether a message was accepted, rejected, or is still in progress. The report response includes counts for success, failure, unsent, sending, and not-found messages, plus a per-message array with the message ID, destination number, timestamp, and status. Use these values to drive retries, alerting, and list hygiene.
Do not retry blindly on every non-success status. Some failures are permanent (invalid number, blocked content) while others are transient (network congestion). Classify the response, apply a bounded retry policy, and suppress numbers that fail consistently. This protects your sender reputation and keeps costs predictable.
Integration and security best practices
Treat API credentials as secrets. Keep them on the server, never in client-side JavaScript or mobile apps, and rotate them if they may have been exposed. Ask our team for the HTTPS endpoint and IP allowlisting before production so credentials are not sent over plain HTTP. Use a dedicated account or credential per environment where possible.
Add timeouts, idempotency keys in your own layer, and a queue for high-volume sends so a downstream outage does not create duplicate messages. Log request IDs and message IDs, but avoid logging full message content or phone numbers longer than your retention policy allows. For SMPP alternatives, see the SMPP page.
Compliance for automated messaging
Automation makes it easy to send at scale, which makes consent and suppression lists more important. Check opt-in status before a marketing send, honour STOP requests across every system, and keep transactional messages separate from promotional ones. Include the sender identity and a help route where local rules require it.
Destination rules still apply: 10DLC registration in the USA, CASL consent in Canada, GDPR and ePrivacy rules in the EU and UK, and sender approval in the UAE. The API does not replace those obligations. Our country pages and pricing page are good next reads before production.
Frequently asked questions
What is an HTTP SMS API?
An HTTP SMS API lets an application send text messages by making standard web requests to a gateway. Send99 accepts GET or POST requests, returns JSON responses, and provides separate calls for balance, sending, delivery reports, and inbound messages.
Which endpoints does Send99 provide?
The documented endpoints cover get balance, send SMS, get report, and get SMS (inbound messages). Each call takes account credentials plus the relevant parameters, such as destination numbers and content for a send, or message IDs for a report. See the API documentation for exact parameters and sample responses.
Does the API support GET and POST?
Yes. The send endpoint accepts both GET and POST. GET is convenient for quick tests, while POST is usually a better choice for production because it avoids putting long message content and credentials in a URL. Use HTTPS and server-side credentials regardless of method.
How do I get delivery reports?
Store the message IDs returned by the send call, then query the report endpoint with those IDs. The response shows success, failure, unsent, sending, and not-found counts plus a per-message status array. Use those statuses to drive retries, alerting, and list cleanup.
Is there a sandbox or free trial?
Yes. Test credits let you validate credentials, send to your own handsets, and inspect real delivery reports before funding a production balance. The trial is intended for testing and staging, not for unregistered high-volume marketing.
How should I secure API credentials?
Keep credentials on the server, never in browser or mobile code, and rotate them if exposed. Ask for the HTTPS endpoint and IP allowlisting before production, separate credentials by environment where possible, and avoid logging full message content or phone numbers beyond your retention policy.