Image-based PDF compression
Compress with one fact in mind: this tool flattens every page
PDFNexa’s compressor renders each PDF page as a JPEG image and rebuilds a new PDF from those images. That can reduce image-heavy files, but it also means searchable text, links, form fields and digital-signature validation do not remain interactive.
This is not lossless optimization.
Use it for a delivery copy when file size matters more than preserving interactive PDF structure.
Set the target before you touch quality
If a portal allows 10 MB and your PDF is 10.8 MB, you need a small reduction. If the same PDF is 40 MB, you may need a stronger compromise. Choosing the strongest setting without a target can destroy readability unnecessarily.
| Setting | What changes | Best use |
|---|---|---|
| Balanced | Higher JPEG quality and render resolution | Documents that only need a moderate reduction |
| Smaller file | More image compression | Email or portal limits where text is still readable |
| Strong compression | Lowest quality option | Only when the size limit matters more than fine detail |
Inspect the fragile content, not only the file size
Small scanned text
Letters can soften or merge. Zoom into the smallest important paragraph after export.
Stamps and signatures
Faint ink and thin strokes can disappear earlier than bold body text.
Charts and screenshots
JPEG artifacts can appear around lines, labels and sharp interface elements.
Why a second compression pass is usually a bad test
If the first result is still too large, return to the untouched original and choose a different setting. Recompressing the already compressed copy stacks image loss and often produces smaller and smaller savings.
When this compressor is the wrong tool
- You must preserve searchable text. Use a PDF optimizer that does not rasterize pages.
- The PDF contains important live forms or links. Flattening will remove that behavior.
- The document carries a certificate-based digital signature. Rebuilding the file changes the signed state.
- The source scan is already blurry. Rescanning can be better than squeezing an already weak image.
A clean compression workflow
- Keep the source unchanged.
- Choose the least aggressive setting likely to meet the target.
- Download the new copy and note its size.
- Inspect small text, signatures, charts and photos.
- If it misses the target, start again from the source with the next setting.
File handling
PDF.js renders the selected document inside your browser; PDF-Lib builds the compressed copy there. The PDF file itself is not uploaded to PDFNexa. External library files are downloaded by the webpage, but your document bytes remain in the browser workflow.