Do my files leave my device when I use Compress PDF?

No. All processing runs in your browser inside a Web Worker. Your files are never uploaded to any server.

What is the maximum file size?

Each file can be up to 50 MB in the browser workspace. Larger files may fail depending on available memory.

What is the difference between lossless and raster compression?

Lossless mode removes redundant internal objects, duplicate fonts, and verbose metadata while keeping text and vectors perfectly intact. Raster mode converts pages to optimized images at your chosen quality, achieving much smaller sizes at the cost of losing selectable text.

How much can I reduce the file size?

Lossless cleanup typically yields 10–30% reduction. Raster compression can reduce size by 50–90% depending on the chosen DPI and the original content (image-heavy PDFs compress more than text-heavy ones).

Will the compressed PDF still be searchable?

In lossless mode, yes — all text remains selectable and searchable. In raster mode, text becomes part of the image and is no longer selectable.

Can I choose the compression quality?

Yes. Raster mode lets you select the output DPI and image quality level. Higher quality means larger files; lower quality means smaller files.

Is Compress PDF free?

Yes, completely free with no watermarks, no sign-up, and no limits on file count.

Does Compress PDF work on mobile?

Yes. The tool runs in any modern mobile browser, though very large files may be limited by your device's available memory.

Compress PDF online free

About Compress PDF

Compress PDF reduces file size through structure cleanup and an optional raster pass — making large PDFs easier to email, upload, and store. Everything runs locally in your browser with no cloud upload.

PDF files often contain redundant objects, uncompressed streams, verbose metadata, and duplicate fonts that inflate size without adding value. Compress PDF cleans up the internal structure and optionally rasterizes pages at a chosen quality level to achieve dramatic size reduction.

The tool uses pdf-lib and Mozilla PDF.js inside a Web Worker, offering two modes: lossless structure cleanup (removes redundancies while keeping text and vectors intact) and raster compression (converts pages to optimized images at your chosen DPI). You see the before-and-after file sizes before downloading.

Because all processing is local, Compress PDF is ideal for reducing the size of confidential documents before sharing. Your files never leave your device.

Last updated: 2026-06-29

How to use Compress PDF

1. Open Compress PDF Navigate to the Compress PDF tool in your browser.
2. Upload your PDF Drag and drop your PDF onto the drop zone or click to browse for the file.
3. Choose compression mode Select lossless structure cleanup for text preservation, or raster compression for maximum size reduction.
4. Adjust quality settings If using raster mode, choose the DPI and image quality. Lower values produce smaller files.
5. Click Process Press Process. The tool compresses the PDF locally — you will see the original and compressed file sizes side by side.
6. Review and download Compare the size reduction, then click Download to save the compressed PDF to your device.

Frequently asked questions

Do my files leave my device when I use Compress PDF?: No. All processing runs in your browser inside a Web Worker. Your files are never uploaded to any server.
What is the maximum file size?: Each file can be up to 50 MB in the browser workspace. Larger files may fail depending on available memory.
What is the difference between lossless and raster compression?: Lossless mode removes redundant internal objects, duplicate fonts, and verbose metadata while keeping text and vectors perfectly intact. Raster mode converts pages to optimized images at your chosen quality, achieving much smaller sizes at the cost of losing selectable text.
How much can I reduce the file size?: Lossless cleanup typically yields 10–30% reduction. Raster compression can reduce size by 50–90% depending on the chosen DPI and the original content (image-heavy PDFs compress more than text-heavy ones).
Will the compressed PDF still be searchable?: In lossless mode, yes — all text remains selectable and searchable. In raster mode, text becomes part of the image and is no longer selectable.
Can I choose the compression quality?: Yes. Raster mode lets you select the output DPI and image quality level. Higher quality means larger files; lower quality means smaller files.
Is Compress PDF free?: Yes, completely free with no watermarks, no sign-up, and no limits on file count.
Does Compress PDF work on mobile?: Yes. The tool runs in any modern mobile browser, though very large files may be limited by your device's available memory.