Compress PDF Online – Free PDF Size Reducer
Reduce your PDF file size by rewriting its internal structure — without re-encoding images or affecting visual quality.
No signup · No limits · Works on any device
What Is a PDF Compressor?
A PDF compressor reduces the file size of a PDF document by optimizing its internal structure. PDFs can contain redundant objects, unused resources, duplicated font data, and unoptimized cross-reference tables — all of which inflate the file size without adding any visible content. A PDF compressor rewrites the file more efficiently, removing this waste without touching the actual images, text, or visible content of the document. This is called "lossless" compression because visual quality is completely preserved. The result looks identical to the original — you cannot see any difference between the input and output. This is in contrast to "lossy" compression, which re-encodes images at lower quality to reduce file size (at the cost of visible degradation). FileQuick's PDF compressor uses pdf-lib's useObjectStreams optimization. Object streams bundle multiple PDF objects into a single compressed stream, typically reducing unoptimized PDFs by 20–50%. PDFs that are already well-optimized may see a smaller reduction. Text-heavy PDFs created from Word documents or other word processors tend to benefit the most. Scanned PDFs (which are essentially just embedded images) see less reduction from this approach since their size is dominated by the image data. All processing runs in your browser. Your PDF never leaves your device, making it safe to use with confidential contracts, financial reports, medical records, or any sensitive document.
Why use FileQuick?
Many PDF compressor tools on the internet achieve size reduction by re-encoding embedded images at lower quality — which makes your document look worse. FileQuick uses pdf-lib's structural optimization approach: it rewrites the PDF's internal object structure into a more efficient format without touching the image data at all. Visual quality is identical to the original. And because it runs entirely in your browser, your confidential documents stay private. No server upload, no cloud processing, no privacy risk.
How to Compress a PDF Online — Step by Step
- Click 'Upload File' or drag and drop your PDF into the drop zone.
- Click 'Compress PDF'. The tool rewrites the PDF's internal structure using pdf-lib's object stream optimization.
- The input and output sizes are displayed with the percentage reduction achieved.
- Click the download button to save the compressed PDF to your device.
Frequently Asked Questions
Is the PDF compressor free?
Yes, completely free — no account, no payment, and no file limits.
Will compression reduce visual quality?
No. FileQuick's compressor rewrites the PDF structure without re-encoding images or altering text. Visual quality is identical to the original document.
How much size reduction can I expect?
Results vary by PDF. Unoptimized PDFs — particularly those exported from word processors — typically see 20–50% reduction. PDFs that are already optimized may see little to no reduction, and the output may be similar in size to the input.
Does it work on scanned PDFs?
Yes, but scanned PDFs are image-based, so structural optimization has minimal impact. Most of the file size in a scanned PDF comes from the embedded images, which this tool does not touch. For scanned PDFs, a dedicated image-resampling compressor would achieve better results.
Are my files stored on a server?
No. All compression happens entirely in your browser using pdf-lib. Your PDF never leaves your device.