Free Compress PDF Online

Reduce your PDF file size instantly — no upload, no account, runs entirely in your browser.

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Click to select or drag & drop your PDF here

1

Select file

Click or drag & drop your file. Nothing is uploaded — it stays on your device.

2

Process instantly

Your browser processes the file locally using JavaScript — fast and completely private.

3

Download result

Your processed file downloads immediately. No waiting, no email, no account needed.

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How Does PDF Compression Work?

PDF compression reduces file size by stripping embedded metadata — author names, keywords, creation tools, revision history and other hidden data that adds weight without adding value. OneConvert uses pdf-lib with object stream compression (equivalent to PDF/1.5 compression) to pack the remaining data more efficiently.

Results vary by PDF: documents heavy with metadata can shrink significantly, while already-optimised PDFs may see smaller reductions. Image-heavy PDFs require deeper compression (resampling images) which is a server-side operation. For those, use our compress tool to remove metadata first, then open in your PDF viewer to reduce image quality.

Frequently Asked Questions

Yes — completely free, no file size limits, no account required.
Depends on the original. Metadata-heavy PDFs can shrink 10-40%. Lean PDFs may see less reduction. The tool shows the percentage saved after processing.
No — this tool strips metadata and uses lossless compression. Page content, images and fonts are not affected.
If the PDF is already well-optimised, the overhead of re-encoding can occasionally add a few bytes. In that case, keep the original.
No. Everything runs in your browser. Your PDF never leaves your device.