How to Compress a PDF Without Uploading It
A browser-local PDF size reducer can decrease PDF size without an upload, but this workflow rasterizes pages and may remove selectable text, links, forms, and document structure.
Read guide →Compress PDF
Reduce PDF file size by re-encoding pages as compressed images. Choose resolution and quality. Runs in your browser — files are never uploaded to a server.
Drop a PDF here or click to browse
This PDF is processed in your browser and is not uploaded to opentools.
Reviewed 2026-07-12
Free Compress PDF – how it works
Compress PDF reduces the size of a PDF document by rendering each page to a raster image at a chosen DPI and re-encoding it as JPEG. This approach shrinks files dramatically, especially PDFs that contain large embedded photos or high-DPI scanned pages, making them easier to email or upload to portals with attachment limits.
Processing is entirely client-side using pdf.js for rendering and jsPDF for re-assembly. No content is sent to a server. The trade-off is that the output PDF contains raster images rather than vector text: the file will be smaller but the text will no longer be selectable or searchable unless you run OCR afterwards.
Use a lower DPI (72–96) and quality (60–70%) for maximum size reduction. Use higher DPI (150–200) and quality (85–90%) to preserve readability for on-screen viewing or moderate-resolution printing.
How to use Compress PDF online
- Upload the PDF. Drop your PDF into the tool. The file is read entirely in your browser — no upload occurs.
- Adjust compression settings. Set the output DPI (resolution) and JPEG quality. Lower values produce smaller files; higher values preserve more detail.
- Compress and download. Click Compress to process the PDF locally. Review the file size reduction, then download the result.
When to use it
- Shrink a large scanned PDF to fit an email attachment limit (typically 10–25 MB).
- Reduce a portfolio PDF for uploading to a job application portal with a size cap.
- Compress a multi-page document before sharing via messaging apps that cap file size.
- Create a lightweight screen-quality copy of a print-resolution report.
Known limitations
- Compression rasterizes vector content — selectable text, clickable links, and vector graphics are converted to pixels.
- Very complex documents or those with many high-resolution pages may be slow to process or run out of browser memory on mobile devices.
- File size reduction is not guaranteed. PDFs already containing compressed images may not shrink significantly.
Frequently asked questions
Is Compress PDF free to use?
Yes, completely free. No account, no watermark, and no limit on how many times you compress a file.
Are my files uploaded when I compress a PDF?
No. The entire compression pipeline runs in your browser tab using pdf.js and jsPDF. Your PDF is never sent to opentools or any third-party server.
Will the compressed PDF still be readable?
Yes, for most screen-viewing purposes. At 108 DPI and 70% quality (the default), text remains legible on screen. For printing, use at least 150 DPI and 85% quality.
Why does the compressed PDF lose searchable text?
The compression method rasterizes every page to an image. The output PDF contains pixel snapshots of each page, not the original vector text. Use an OCR tool if you need to restore text selection.
How much can I reduce the file size?
A scanned PDF at 300 DPI can typically be reduced by 60–80% at 96 DPI / 70% quality with no visible difference on screen. PDFs already containing heavily compressed images will shrink less.
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