Using the FTP API



SMS messages are sent by uploading a specially formatted text file to the Clickatell FTP server. Each text file can contain up to 100 000 messages/mobile numbers. To send larger numbers of messages, simply upload multiple files with up to 100 000 messages each. One text file can contain a single message to all recipients or unique messages for each handset.

Each FTP API connection created within your Developers’ Central account will give you access to an FTP folder on our server (accessible with a username and password).

Our platform processes newly uploaded files for all FTP folders once a minute. Due to this interval, the API is not ideal for highly time-sensitive messages such as one-time pin codes (OTPs). For such time-sensitive messages we recommend one of our HTTP based APIs (HTTP/SOAP/REST/XML) or the SMPP API.


  • To send many messages, use one text file (instead of many files with one message per file).
  • Files in your FTP folder are automatically deleted 48 hours after the last modification.
  • We accept plain-text files with DOS, MAC or UNIX line breaks.
  • Each line in the text file may be a maximum of 8192 bytes.

Send your first message

To send your first message you will need:

  • Your FTP server login details.
  • Your API username, API password and API ID to use in the text file.
  • An FTP client application (such as FileZilla).

See here for information on where to find these two sets of authentication credentials.

Step 1:
 Copy and paste the sample below into a text editor (such as Notepad).

text:This is my message being sent to 3 mobile numbers.

Step 2:
 Enter your authentication details.

Step 3:  Replace one/all of the example mobile numbers with your mobile number. It needs to be in international format:

  • The mobile number needs to start with the correct country code.
  • It must contain no spaces or other non-numeric characters.
  • If the mobile number starts with zero, remove the zero before typing the rest of the number.

Step 4: Log in to the FTP server at ftpupload.clickatell.com.

Step 5: Upload your text file with the contents from above.

  • You can add as many to:xxxx lines as you wish.
  • Until you make a purchase, your messages will contain pre-defined content.

Read more about sending messages here.

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