API keys were added in response to problems with high volumes of requests for callsign to DXCC lookups which originated in an experimental logging program. The various interfaces to Club Log are now protected to help prevent situations where external applications can interfere with the operation of the web site, and to improve visibility of who is using the API and for what purpose. They also let me run different versions of the API for different programs and maintain backwards compatibility.
You will see this message if you access Club Log APIs but do not provide an API key. An API key is specific to your application and looks roughly like this: 0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33.
You do not need a key unless you write software which integrates with Club Log.
Please do not ask for an API key for use solely to delete QSOs via an HTML form. If you need to delete a QSO, upload a new ADIF and use the 'clear' option or use the delete option on the Log Inspector. Thanks!
To obtain a key please email the helpdesk with a brief overview of your use. There is a list of products which use the Club Log API on which you can choose to be included, if you indicate your preference when you request the key.
Once you have your key, you need to send it with your requests to Club Log. The API key should be sent as a form variable, normally as part of the POST or GET request. There are further notes on this on the Help page. There are also working test forms on that page to help you verify that your API key is working ok.