WhatsApp Business API

The APEX Messaging WhatsApp API allows you to send and receive WhatsApp messages, including OTPs, template-based promotions and notifications, using a secure HTTP interface.

The API is built on top of the official WhatsApp Business Platform and supports both immediate and scheduled messaging, delivery reports, and template management.

Please note that there are requirements of registration and verification requirements before being able to execute messaging on the WhatsApp Business API. For more information about the prerequisites, please visit the WhatsApp Business Platform Access page of the Developer Hub.

Base API URL

All WhatsApp API requests are made to:

https://papi.apex-messaging.com/whatsapp

Authentication

All requests require a valid API key.

The API key is passed using the ApiToken parameter in each request.

API keys are created and managed from the APEX Dashboard under Manage API.
IP whitelisting is required for all API keys.

WhatsApp Messaging Model

WhatsApp messages are sent using approved templates.
Templates are created, submitted, and approved before they can be used for outbound messaging.

Common use cases include:

• OTP Authentication
• Account notifications
• Transactional Alerts
• Utility messages

Sending an OTP Message

This endpoint is designed specifically for OTP delivery over WhatsApp.

Endpoint

https://papi.apex-messaging.com/whatsapp/SendOtp

Request Body (JSON)

{
  "PhoneNumber": "35699999999",
  "OtpCode": "1234",
  "ApiToken": "YOUR_API_KEY",
  "CallbackUrl": "https://yourdomain.com/whatsapp-dlr",
  "TemplateId": "3"
}

Parameters

Parameter	Description	Notes
PhoneNumber	Recipient WhatsApp number in international format	eg. 44xxxxx, do not include a + symbol
OtpCode	OTP value to be sent
ApiToken	Your API authentication token	Found in the dashboard under Manage API
CallbackUrl	Optional URL for delivery status updates
TemplateId	Approved WhatsApp OTP template ID	Found in: Dashboard → WhatsApp → Manage Templates

Success Response

{
  "IsSuccess": true,
  "ErrorCode": 0,
  "ErrorDescription": "Message Accepted",
  "ReturnData": 001
}

ReturnData contains the generated WhatsAppCampaignId, which can be used to fetch delivery reports.

Sending a Template Message (Non-OTP)

Template messages allow you to send approved WhatsApp templates to one or more recipients.

This endpoint supports both application/json and multipart/form-data

Use JSON when sending template messages without media or file-based recipient lists.
Use multipart/form-data when uploading template media or bulk recipient files.

Messages can be sent:

• Immediately
• or scheduled for a future date and time

Endpoint

https://papi.apex-messaging.com/whatsapp/SendMessage

Sending a Template Message (With Media)

multipart/form-data is an HTTP-standard request encoding that allows structured fields and binary files to be transmitted in a single request.

Use this format whenever uploading template media (images, documents) or recipient files (CSV).

Parameter Name	Type	Description
ApiToken	String	Required. API token used for authentication.
TemplateId	String	Required. ID of the WhatsApp template to be used.
QuickNumber	String	Required if QuickNumberFile is not provided.
CallbackUrl	String	Optional. Callback URL for delivery status.
CampaignName	String	Optional. Name of the campaign.
Sample	String	Optional. Sample data to populate the template.
ButtonExample	String	Optional. URL for template button (if any).
TemplateFile	File	Optional. Template media file.
TemplateFileExtension	String	Optional. File extension of template file.
QuickNumberFile	File	Required if QuickNumber is not provided.
QuickNumberFileExtension	String	Optional. File extension of quick number file.
QuickNumberFileColumn	String	Required if QuickNumberFile is provided.
IsScheduled	Boolean	Optional. Schedule message delivery.
TimeZoneId	Byte	Required if IsScheduled is true.
FinalEffectiveDate	DateTime	Required if IsScheduled is true.
FinalEffectiveTime	TimeSpan	Required if IsScheduled is true.

Request Body (multipart/form-data)

curl -X POST https://papi.apex-messaging.com/whatsapp/sendmessage \
  -H "Authorization: YOUR_API_TOKEN" \
  -F "TemplateId=template_12345" \
  -F "QuickNumber=971501234567" \
  -F "CallbackUrl=https://client.example.com/whatsapp/dlr" \
  -F "CampaignName=April Promo Campaign" \
  -F "Sample=John Doe,Order12345" \
  -F "ButtonExample=https://www.example.com/track" \
  -F "TemplateFile=@promo-image.jpg" \
  -F "TemplateFileExtension=jpg" \
  -F "IsScheduled=true" \
  -F "TimeZoneId=2" \
  -F "FinalEffectiveDate=2025-04-28" \
  -F "FinalEffectiveTime=23:12:00"

Bulk send example (using a number file)

curl -X POST https://papi.apex-messaging.com/whatsapp/sendmessage \
  -H "Authorization: YOUR_API_TOKEN" \
  -F "TemplateId=template_12345" \
  -F "QuickNumberFile=recipients.csv" \
  -F "QuickNumberFileExtension=csv" \
  -F "QuickNumberFileColumn=phonenumber" \
  -F "CampaignName=Bulk WhatsApp Campaign" \
  -F "Sample=Jane,Invoice9981" \
  -F "TemplateFile=@document.pdf" \
  -F "TemplateFileExtension=pdf"

Sending Template Message (No Media)

You can use JSON or multipart/form-data when sending template messages without media or file-based recipient lists.

{
  "ApiToken": "YOUR_TOKEN_HERE",
  "TemplateId": "873646267282931",
  "QuickNumber": "35699384535",
  "CallbackUrl": "https://webhook.site/DLRS",
  "CampaignName": "ABC",
  "Sample": "Variable 1, Variable 2",
  "ButtonExample": "https://apex-messaging.com/example",
}

Please note that this API document is a work in progress; we will be adding the responses and error codes in due course. If you require further details, please do not hesitate to contact your account manager or our general support.