With the SMS API, anyone can build reliable SMS messaging services using our infrastructure. It is available as a free demo version too. Send some test SMS messages and experiment with the API before taking it into production. In your API Store account you can apply to take the SMS API into production.

API specification

Test the API on SwaggerHub

Base URL

Conceptual model

Conceptual model



An abbreviation of Short Message Service. It's a service on mobile phones to send and receive short messages.

API workflow

API workflow

Features and constraints


  • Send a text message to another mobile phone number.


  • No images can be sent with SMS.
  • Messages longer than 160 characters will be sent as multiple SMS messages.
  • A single message can be sent to a single recipient. Bulk messaging will be added in the future.
  • With this API, messages can only be sent to mobile phones registered in the Netherlands. So the country code is locked to +31. Also 097 range is allowed.

060xxxxxxx, 067xxxxxxx and 069xxxxxxx are not valid mobile numbers.

Getting started

Make sure you've read What's in it for you for more info on how to register and start testing APIs.


The API follows the KPN Store API Authentication Standard to secure the API. It includes the use of OAuth 2.0 client_id and client_secret to receive an access token.

Go to the Authentication tab on top of this page to find out how to:

  • Authenticate to an API using cURL.
  • Authenticate to an API on Swaggerhub.
  • Import Open API Specifications (OAS), also called Swagger files into Postman.

How to...

Send SMS

Send an SMS by calling the POST /send endpoint of the SMS API in Swaggerhub or Postman.

Keep in mind that messages can only be sent to Dutch mobile phones (country code +31).

Create your payload for the request using below snippet:

^^Request example^^
  "sender": "KPN API",
  "messages": [
      "mobile_number": "06xxxxxxxx or +316xxxxxxxx",
      "content": "Hi from KPN!"

The payload uses following parameters:

Parameter Description
sender A text that should resemble the sender's origin. This string can have a maximum length of 11 characters.
mobile_number The mobile phone number of the addressee. Use the country code +31 at the start.
content Put your message here. Long messages will be split into multiple SMS.


  1. Select POST /send.
  2. Click Try it out.
  3. Edit the body parameter by providing the payload snippet above. In the payload change the content, mobile_number and sender to your own good. Make sure the content-type is set to application/json.
  4. Click Execute.
  5. Check the response code and message.


  1. Select (POST) /send.
  2. In the Body section, set the type to raw and insert the payload snippet above. In the payload change the content, mobile_number and sender to your own good. Make sure the content-type is set to application/json.
  3. Click Send.
  4. Check the response code and message.

Result example:

^^Response example^^
  "document_id": "b4e905d4-774c-4c83-8360-01427e17a33a",
  "status": "OK"

Return codes

Code Description
200 Success.
201 Created.
202 Accepted.
302 Found. Link in location header.
400 Bad request.
401 Unauthorized.
403 Forbidden.
404 Not found.
405 Method not allowed.
412 Precondition failed.
429 Too many requests.
500 Internal server error.
502 Bad gateway.
503 Service unavailable.

HTTP response headers

The following tables display the standard response headers that are returned with each API response:

Standard response field name Description
sunset This field will be populated with the deprecation details. By default the value is n/a.
api-version Indicates the API version you have used.
quota-interval Used to specify an integer (for example, 1, 2, 5, 60, and so on) that will be paired with the quota-time-unit you specify (minute, hour, day, week, or month) to determine a time period during which the quota use is calculated.
For example, an interval of 24 with a quota-time-unit of hour means that the quota will be calculated over the course of 24 hours.
quota-limit Number of API calls an user can make within a given time period.
If this limit is exceeded, the user will be throttled and API requests will fail.
quota-reset-UTC All quota times are set to the Coordinated Universal Time (UTC) time zone.
quota-time-unit Used to specify the unit of time applicable to the quota.
For example, an interval of 24 with a quota-time-unit of hour means that the quota will be calculated over the course of 24 hours.
quota-used Number of API calls made within the quota.
strict-transport-security The HTTP Strict-Transport-Security (HSTS) response header lets a website tell browsers that it should only be accessed using HTTPS, instead of using HTTP. All present and future subdomains will be HTTPS for a maximum of 1 year and access is blocked to pages or sub domains that can only be served over HTTP including HSTS preload lists of web browsers.
Strict-Transport-Security: max-age=31536000; includeSubDomains; preload.
Access control field name Description
access-control-allow-credentials Tells browsers whether to expose the response to frontend JavaScript when the request's credentials mode (Request.credentials) is include.
When a request's credentials mode (Request.credentials) is include, browsers will only expose the response to frontend JavaScript if the Access-Control-Allow-Credentials value is true. Boolean.
access-control-allow-origin Indicates whether the response can be shared with requesting code from the given origin.
access-control-allow-headers Used in response to a pre-flight request which includes the Access-Control-Request-Headers to indicate which HTTP headers can be used during the actual request.
access-control-max-age Indicates how long the results of a pre-flight request (that is the information contained in the Access-Control-Allow-Methods and Access-Control-Allow-Headers headers) can be cached.
access-control-allow-methods Indicates which HTTP methods are allowed on a particular endpoint for cross-origin requests.
For example: GET, PUT, POST, DELETE.
content-length The Content-Length entity header indicates the size of the entity-body, in bytes, sent to the recipient.
content-type The Content-Type entity header the client what the content type of the returned content actually is.

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