Quick answer
What is Compress PDF used for?
Purpose
What does Compress PDF do?
Expect a separate PDF with a measured size change, not a guaranteed percentage reduction. Open small text and signatures at reading size.
Who normally uses it?
This guide is useful for people preparing PDFs for upload limits, printing, email, filing, or long-term storage. The working tool is focused on one outcome: Smaller file, checked against the original before you get it.
Prepare
Before you start
- Decide whether the priority is smaller size, cleaner page edges, compatibility, or visual quality.
- Keep the original because optimization can intentionally remove editable or unused document data.
- Open image-heavy or scanned pages at normal reading size so quality changes are easy to notice.
Worked example
Reduce a scanned application for a portal with a strict upload limit.
This example describes a practice task, not a document you need to upload to us. Use your own authorised file and keep the original.
- 01
Prepare the example
Keep the original scan and note its size and the portal limit before choosing the file.
- 02
Make the change
Enter the portal limit in KB or MB, or leave the target blank. Compression combines safe repacking with verified font compaction, without reducing image quality.
- 03
Check the result
Expect a separate PDF with a measured size change, not a guaranteed percentage reduction. Open small text and signatures at reading size.
When the result is not right
Troubleshooting Compress PDF
If the result is still above the limit, split into acceptable pieces if the portal allows it, or start from smaller source images. Avoid repeatedly compressing the same result.
Before you rely on the output
Already-compressed PDFs may not shrink. An unmet target is reported honestly: the tool does not sacrifice image quality or remove document content. Signed PDFs and XFA forms are returned unchanged.
Open the saved result as well as the preview. Keep the original until you have checked the pages and information that matter for your task.
Better results
Practical tips for Compress PDF
Try the least destructive option first, then increase compression or cropping only when needed.
Compare both the byte size and the visible page quality instead of trusting a promised percentage.
Inspect thin text, diagrams, signatures, and photographs after processing because they reveal quality loss first.
Honest expectations
Limitations and important checks
The amount saved depends on what the PDF contains. A file that is already compressed may become only slightly smaller.
Questions and answers
Compress PDF FAQ
Direct answers to the questions people commonly ask before using this tool.
What is Compress PDF used for?
Compress PDF is a browser-based Filozy tool built for this task: Smaller file, checked against the original before you get it. It runs on this device, creates a separate result, and does not require an account or document upload.
Can I use Compress PDF on a phone or tablet?
Yes. Compress PDF works in a current mobile browser. Complex PDFs can need more memory, so keep the tab open, avoid switching apps during processing, and inspect the result before closing the page.
How do Maximum, Balanced and Minimal differ?
All levels preserve content and image quality. Minimal only repacks storage. Balanced additionally checks fonts of at least 32 KiB, up to 2 MB decoded, in documents of up to 20 pages. Maximum checks supported fonts up to 4 MB decoded in documents of up to 80 pages. Font changes require the same full-page preservation checks in both modes. Some documents produce the same result at different levels.
Can I compress a PDF to an exact size without changing its appearance?
You can set a maximum size in KB or MB, but not every PDF can reach it without quality loss. Filozy reports whether the target was met and will not remove content or degrade images to force the result.
Does compression preserve text, fonts and form fields?
The compressor checks repacked document objects and may compact supported embedded fonts while retaining every glyph ID, shape and spacing. Font compaction requires an all-page pixel and text-position comparison; if verification is unavailable or fails, it falls back to safe repacking. Images and form appearances are not reduced in quality. Signed PDFs and XFA forms remain unchanged. Always review the output in your PDF viewer.
Does Compress PDF upload my file?
No. The selected file is opened and processed by code running in this browser tab. Document bytes and filenames are not sent to Filozy.
Will this change my original file?
No. Browsers cannot silently overwrite the file you selected. Filozy creates a separate result for you to save or pass to another local tool.
What should I check after using Compress PDF?
Check the visible preview and the result summary. The result reports the real byte change instead of promising a percentage before examining the document. Keep the original until the new output has been opened and verified.
Privacy
Where does my document go?
For this tool, the document stays in the browser tab. Filozy can load same-origin support files such as its PDF engine, fonts, or OCR data, but the selected document bytes and filename are not sent with those requests.