Free Compress PDF Online

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

PDF compression reduces file size by stripping embedded metadata, revision history, creator information and redundant data that accumulates in PDFs from various applications. The result is a leaner file that attaches faster in emails, uploads quicker to cloud services and takes less storage — without any visible change to content, fonts or images. Everything runs in your browser using pdf-lib.

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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.
If the PDF is already optimised or contains mostly images with embedded compression, the metadata removal has less impact. Image-heavy PDFs require resampling images, which is a server-side operation beyond what this browser tool handles.
Yes — this tool removes metadata and re-encodes PDF streams more efficiently. No content, image quality or text is affected.