Is compression lossless?

Not in general. UnderLimit aims for readability-aware compression toward your target. We do not claim zero quality loss.

When should I use Strong?

When analysis shows Preserve/Balanced cannot approach the limit and the document is image-heavy. Always review the result.

Compress scanned PDFs without guessing

Scanned PDFs are mostly pictures of pages. That is why they balloon past portal limits. UnderLimit’s preflight shows whether Preserve, Balanced, or Strong is realistic for your target.

Drop up to 20 PDFs here

Max 150 MB per file · 500 MB total

Files are scanned before analysis.

Target

Mode

Why scanned PDFs get large

Each page may embed a high-resolution image. Colour scans, phone photos, and multipage stacks multiply size far faster than born-digital text PDFs.

Preserve, Balanced, and Strong

Preserve favours structure when possible. Balanced seeks a middle path. Strong may downsamples images more aggressively and can rasterize pages when that is the only way to approach a tight limit.

Readability trade-offs

Official uploads need readable names, stamps, and figures. If Strong would make text hard to read, raise the target instead of forcing an unusable file.

Batch scanned documents

Prepare up to 20 scanned PDFs in one batch, share a target, and download files or a ZIP when background processing finishes.

FAQ

Is compression lossless?: Not in general. UnderLimit aims for readability-aware compression toward your target. We do not claim zero quality loss.
When should I use Strong?: When analysis shows Preserve/Balanced cannot approach the limit and the document is image-heavy. Always review the result.