UnderLimit Support
UnderLimit compresses still images, and version 1.1 adds single-PDF compression. Version 1.0 currently on the App Store supports images only; PDF support becomes available when version 1.1 is released.
Supported images
Choose one JPEG, HEIC or PNG still image from Photos or Files. The image can be up to 250 MB, 50 million pixels and 32,768 pixels per edge. UnderLimit exports a new JPEG copy. Animated images and video are not supported.
PDF support in version 1.1
Choose one PDF from Files. It must be no larger than 100 MB and no more than 50 pages. Invalid, signed and encrypted PDFs are rejected.
UnderLimit creates a new flattened visual PDF. It keeps the page appearance but removes searchable text, links, forms, annotations and other interactive behaviour.
File-size limits
Choose a decimal target from 10 KB through 100 MB. UnderLimit measures the finished copy on disk before reporting that it is under the selected limit. If a PDF cannot reach the requested limit above the app’s legibility floor, UnderLimit reports the target miss and does not publish the result.
Troubleshooting
If UnderLimit cannot access a file, choose it again from Photos or Files. If it reports that the file is too large, invalid, signed or encrypted, choose a file that meets the limits above.
Export
UnderLimit never modifies the original. After compression, choose the export action and select a destination in the system share sheet.
Privacy
UnderLimit processes images and PDFs locally on your iPhone. It has no account, cloud processing, analytics or tracking, and the developer does not collect app data.