Everything you need to know about compressing PDF files online for free — covering quality, limits, privacy and how much you can save.
Is this tool really free?
Yes — completely free, no subscription, no account, no limits. You can compress as many PDFs as you like at any time.
Are my files sent to a server?
No. Everything runs in your browser using JavaScript. Your file is never uploaded, stored, or processed anywhere outside your device.
Why isn't my file getting much smaller?
Browser-based compression focuses on structural optimisation. PDFs with mostly text compress less than image-heavy ones. Try Maximum level with all options enabled for best results.
Will compression damage my PDF?
Screen and eBook levels are completely safe for all documents. Printer and Maximum levels may affect complex layouts or embedded fonts but will not corrupt the file.
Can I compress password-protected PDFs?
Yes. The tool attempts to load encrypted PDFs with ignoreEncryption enabled. If the PDF is locked with restrictions, results may vary.
Does it work on mobile?
Yes. All features are fully responsive and work on smartphones and tablets using Chrome, Firefox, or Safari on iOS and Android.
Is compression lossless?
The structural compression is lossless — it removes waste without changing visible content. Stripping options (metadata, annotations, forms) remove those specific elements but don't degrade the remaining content.
Does it re-compress images?
This tool focuses on structural optimisation rather than deep image re-encoding. For image-heavy PDFs, downscaling the images before creating the PDF gives the biggest reduction.
Will my fonts still look right?
At Screen and eBook levels, fonts are untouched. At Printer and Maximum, some optional font data may be stripped — text still displays, though very unusual fonts could fall back.
Is there a watermark on the output?
Never. No watermark, no added pages, no branding. Your compressed PDF contains only your content, just stored more efficiently.
What's the maximum file size?
There's no hard cap — only your browser's available memory. In practice, hundreds of MB work fine on desktop; mobile devices are more limited.
Can I undo compression?
The compressed file is a new download — your original is untouched on disk. If you want a different result, re-compress the original with different settings.
Why did my file get bigger?
Rarely, an already-optimised PDF can grow slightly when re-saved. The tool detects this and reports the file as already optimised rather than forcing a larger output.
Does removing metadata help privacy?
Yes. Metadata can include author names, software used and timestamps. The Remove Metadata option strips all of it — useful before sharing externally.
What does flattening forms do?
It converts fillable form fields into static page content. The form can no longer be edited, the answers are locked in, and the form overhead is removed — shrinking the file.
Can I compress multiple PDFs at once?
This tool compresses one file at a time, but there's no limit on how many files you run back-to-back. Each compression takes only seconds.
Will compressed PDFs open everywhere?
Yes. The output is a standards-compliant PDF that opens in Acrobat, Preview, Chrome, mobile readers and any other PDF viewer.
Does it work offline?
Yes. Once the page and the pdf-lib library have loaded, you can disconnect from the internet and the compressor still works.
How do I get the best reduction?
Use Maximum level with Remove Metadata, Remove Annotations and Flatten Forms all enabled. For image-heavy files, also reduce image resolution before creating the PDF.
Is there a daily limit?
No. Compress as many PDFs as you want, as often as you want. There's no quota, no rate limit, and no premium tier.