The task: Combining multiple PDF files (1,2) to one PDF file.
As always, we need a Process URL first. Therefore we need our personal API Key. We do set mode to combine. Click "Execute" to request the Process URL.
Using the obtained Process URL, the process is started using the following request. We set input to download and files to an array, containg the input files. We set wait to true to block the request until the conversion is finished.