The app uses rewarded video ads - restoration of any discovered file or data is completely free of charge. You can still buy the unlocker to remove all ads and enable background scanning.
Without root access, Undeleter can only scan app caches for images.
App caches can contain images that would not otherwise be discoverable: you may find photos that were shared with you on social media but you never opened, or lower quality copies of images you have now or have deleted in the past. They may also contain images that have been preloaded by your browser or other apps on your device - even images of people you don't know. They can be filtered out using "Hide extant files".
Deep scan heuristically scans for and recovers the following types of files: BMP, JPEG/JPG, PNG, MNG, JNG, GIF, MP4, AVI, MKV, MP3, OGG, OGM, WAV, FLAC, AMR, MP4A, PDF, SXD, SXI, SXC, SXW, ODT, ODG, ODS, ODP, DOCX, XLSX, PPTX, ZIP, JAR, APK, EPUB.
Data scanning is available for a select number of apps. Data will be recovered in the form of HTML files for WhatsApp and Viber, as third-party catalogs cannot be merged.
Shred/ secure delete - files found on free disk areas can be erased permanently in bulk using the Shred function. You can also use the system-wide Share menu to securely erase files directly through any other app, for example by opening the gallery, selecting a number of images, pressing the Share button and selecting Secure delete.
Permissions - all of these are necessary for various functions, this is not a time wasting game, its an app for adults that was written from the ground up to restore deleted data. There's no catch, no trick. Read the instructions, Google the terms if you don't understand them. You will get what you need if you pay attention to what you're doing.
You can check permission details below, where it says "App info" > "App permissions". Click on "See more" to examine all of them.
CONTACTS - needed for Google Drive and Dropbox upload, used to discover connected accounts
LOCATION - for ads, I don't use Admob any more, which would extrapolate your location without your permission regardless
I do not provide technical support beyond app updates. Crash logs are welcome unless you are using Xposed.