Compression guide
Reduce visual PDF weight with an explicit tradeoff
PDF Compressor is for making one document easier to attach, upload or store. Recommended, High Quality and Extreme render each page and rebuild it from compressed page images. That approach can reduce image-heavy files, but it trades away document structure. Preserve document structure instead rewrites supported PDF objects without rasterizing every page, so reduction may be modest.
How to compress and check the result
- STEP 1
Add one PDF
Choose a valid PDF no larger than 100 MiB. The compressor checks the file locally.
- STEP 2
Choose the outcome
Start with Recommended. Select High Quality for detailed pages, Extreme for a smaller visual copy, or Preserve for supported text and interactive structure.
- STEP 3
Compare before sharing
Download the result, check the reported size and inspect small text, images, links, forms and page count against the original.
Useful for
Email attachments, portal upload limits, image-heavy scans and disposable viewing copies where appearance matters more than editing the PDF later.
Not the same as optimization without change
Compression cannot guarantee a smaller file or unchanged quality. Already optimized PDFs may not shrink, and raster modes can soften detail or increase a text-only file.
Private browser processing
Document bytes are handled on the current device. Rendering and output generation can use substantial memory, especially on mobile devices or pages with large images.
Compressor boundaries
One PDF, up to 100 MiB and 80 pages. Password-protected, corrupt, empty or memory-heavy files can be rejected. Output is a PDF.
Troubleshooting compression
The result looks soft
Retry with High Quality or Preserve document structure and compare at normal reading zoom.
The file did not shrink
The source may already be efficient. Avoid repeated recompression; use Split PDF if only part of the document is needed.
The browser runs out of memory
Close other large tabs, try a desktop browser, or split the document into fewer pages before compressing.
Links, forms or signatures matter
Use Preserve mode and verify the download. Any rewrite can invalidate a digital signature, so retain the signed original.
Choose the page task you actually need
Use the PDF quality tradeoff guide when reducing bytes is the goal. If file size is secondary and mixed physical page dimensions are the problem, use Normalize PDF Page Size; that rewrite may make the file larger.
PDF Compressor questions
Why can compressed PDF text stop being selectable?
Recommended, High Quality and Extreme rebuild pages from rendered images to reduce visual content. That can flatten text, links, forms, annotations, layers and signatures. Choose Preserve document structure when those features matter more than reduction.
Why is the compressed PDF not much smaller?
A PDF that already uses efficient images or mostly contains text and vectors may have little removable data. Preserve mode can also produce a similar-sized file because it keeps supported document structure.
Which compression mode should I try first?
Recommended is the starting point for ordinary sharing. Use High Quality for small text or detailed graphics, Extreme only when file size matters most, and Preserve document structure for searchable text, links or forms.
Can I compress a password-protected PDF?
Not in the current compressor. Open a file you are authorized to use with the Unlock PDF tool first, then review the unlocked result before compression.
What are the PDF Compressor limits?
The browser workflow accepts one valid PDF up to 100 MiB and 80 pages. Complex pages can still exceed the device's available canvas memory.
Does FiloTool upload the PDF for compression?
No. The selected PDF is read, rendered or rewritten, checked and prepared for download on your device. FiloTool does not receive the document bytes.
Available choices: Recommended, High Quality, Extreme and Preserve document structure.