At first, you have to specify which PDF Documents to compress.
This can be done easily in many ways. Press the "Add File" button to add select one or more PDF Documents, or press the "Add Folder" button to select an entire Folder and add all the PDF Documents that are in this folder.
Alternatively, you can simply right click on the PDF Documents in Windows Explorer and select "Compress PDF Document" from the context menu. In order to do this, you should have checked the option "Integrate with Windows Explorer" during the installation.
Another easy way to add PDF Documents is to drag and drop them on the application window.
You can also import a list of PDF documents to compress.
To do so, create a text file listing all PDF files to be compressed, one PDF file or folder at each line.
If your PDF file or folder requires a user password (for opening) write in a line the PDF file or folder and a comma and the password. For example
To compress the documents and its images check the "Compress Images" checkbox.
To set the desired image quality, enter a value from 0-100 in the image quality textbox.
To compress PDF documents enter the "User Password" (the one that is used for opening them) in the grid or when you will be prompted for the password.
After you have specified which PDF documents to compress, press the "Compress" button.
In the end, Windows Explorer will open automatically with the protected documents having being selected.
It is also possible to specify the output folder of the compressed PDF Documents. If it is selected to be the same folder as the documents folder then the compressed document will have the same filename as the original document but will end with "_compressed.pdf". If another folder is specified then the modified pdf document will have the same filename as the original one.
You can also choose to overwrite the original documents (and keep a backup of the changed files) or to create the modified PDF documents in a subfolder of their original folder.
For example, you can specify to create them in a subfolder "compressed". 4dots Free PDF Compress remembers your last five output folder options.
You can open or explore a selected PDF document, simply by right clicking it on the grid and selecting "Open", or "Explore", from the context menu, accordingly.
Read here command line usage
When the application is first started it asks you for your desired user interface language.
You can also change the user interface language from the "Language" menu.