PDF Crop is a free Android app that lets you crop PDF documents with ease. You can import documents from your device storage or from cloud storage services such as Dropbox, Google Drive, OneDrive, and Box. Once the document is inserted, you can select the pages that you want to include in the output document by tapping on them. Then, tap on the Crop button in the upper left corner and wait for the app to do its thing.

PDF Crop processes the documents on its powerful servers, so it won't burden your phone's processor or battery. You can perform an unlimited number of crop tasks, and the app is very quick and easy to use. You can choose between free cropping, which takes 1 hour to complete, or fast cropping, which is completed in seconds. After you get the result, the app will delete your documents from its servers.

Overall, PDF Crop is an excellent app for anyone who needs to crop PDF documents on the go. It's quick, easy to use, and it supports a wide range of cloud storage services.