For custom services we offer FTP. We generally recommend using our standardised API, but for certain use cases FTP deployment is required. FTP is an old protocol with some weaknesses and problems.
Our FTP-Server is available at: ftp.meteoblue.com
Per default FTP transmits everything unencrypted in plaintext. "Man in the middle" attacks can easily capture login credentials with username and password. We recommend using FTP-SSL (over TLS) to encrypt control and data channels. For the popular FTP client "File Zilla" you should configure your FTP session with "Encryption" > "Require Explicit FTP over TLS"