UnderLimit

Choose a KB or MB maximum. UnderLimit creates a verified image or flattened PDF copy when the maximum is reachable—on your iPhone, with no account or subscription.

Create a verified photo or supported PDF copy under a file-size maximum when the source can safely reach it—without uploading it anywhere.

UnderLimit is a focused, private file compressor for the moments when a form, portal, email, or message rejects an image or document as too large.

HOW IT WORKS — IMAGE OR SINGLE-PDF SHRINKING

1. Select one JPEG, HEIC or PNG from Photos or Files, or one supported PDF from Files.
2. Enter a maximum from 10 KB to 100 MB, using decimal KB or MB.
3. Compress the image or flatten the PDF, then save or share the verified copy.

Single-PDF shrinking supports one unencrypted, unsigned PDF up to 100 pages within the supported PDF envelope. Image-heavy PDFs may be rejected when their decoded image data is not safe to process on the device, and some inline-image PDF formats are not accepted; protected or interactive PDFs may also be rejected.

Image compression accepts one JPEG, HEIC or PNG still image up to 250 MB, 50 million pixels and 32,768 pixels per edge. It creates a new sRGB JPEG; transparent backgrounds become white and source metadata, including GPS, is not retained. Batch image compression accepts 2–10 images and applies the same source and pixel limits separately to each image. Verified images that finish before another batch item fails remain available.

HOW IT WORKS — COMBINING PDFs

1. Select 2–10 supported PDFs.
2. Arrange them and review the separate 50-page-total and 100 MB-total limits. UnderLimit checks compatibility before it writes a result.
3. Combine the PDFs and share the verified PDF. Combining has no target-size guarantee.

UnderLimit measures the finished image or flattened single-PDF on disk before it says the result is under your selected maximum. If that maximum cannot be reached without an unreadable result, UnderLimit reports that instead of presenting an unverified copy. Your original is never modified.

BUILT FOR ONE JOB

Custom decimal KB and MB limits, 1 MB/5 MB/10 MB presets, verified byte counts and dimensions, JPEG export, single-PDF flattening up to 100 pages and 100 MB source input, and PDF combining for 2–10 supported PDFs up to 50 total pages and 100 MB total input.

PDF LIMITS

PDF shrinking creates a new flattened visual copy. It removes searchable text, links, forms, annotations and other interactive behaviour. Encrypted and signed PDFs are not compressed, image-heavy PDFs can be rejected when their decoded image data is not safe for on-device processing, and some inline-image PDF formats are not accepted. PDF combining preserves supported document structures but rejects encrypted, signed and unsupported interactive structures. These are separate workflows with separate limits; not every PDF is compatible.

IMAGE LIMITS

Images must be JPEG, HEIC or PNG still images. Animated images and video are not supported. The original is never modified; the exported JPEG is a new sRGB copy and does not retain source metadata, including GPS. Transparent image areas are rendered white.

PRIVATE BY DESIGN

Image and PDF processing happens on your iPhone. UnderLimit has no account, advertising, analytics, tracking, cloud processing, or third-party SDK. It does not collect your photos, files, usage, or diagnostics.

UnderLimit uses app-private temporary working copies and cleans them when the session ends. Launch cleanup removes abandoned session files. You decide when and where to export the finished JPEG or PDF.

CURRENT VERSION

UnderLimit handles still images, single-PDF shrinking and PDF combining. Image compression accepts JPEG, HEIC and PNG input and exports JPEG. Single-PDF shrinking accepts one supported, unencrypted, unsigned PDF up to 100 pages and 100 MB source input, subject to a decoded-image memory safety check. Combining accepts 2–10 supported PDFs up to 50 total pages and 100 MB total input. Video is not supported.

One honest purchase. No subscription and no usage quota.