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Compress a PDF without uploading it

Shrink large PDFs for email or storage. Safe mode keeps text selectable; Strong mode rebuilds pages as images for bigger savings.

Drop your PDF here

or click to browse

PDF only · up to 100 MB per file

Your files never leave your device

All processing happens in your browser. Nothing is transmitted to a server.

Need these pages as images instead?Convert to PNG / JPG

How it works

  1. Add the PDF to shrink

    Drop your file or browse to select it. Compression runs in your browser tab. The original is never sent to a server.

  2. Pick Safe or Strong

    Safe strips unused data and keeps text searchable. Strong rebuilds pages as JPEG images for much smaller files.

  3. Download the smaller file

    Start compression, compare the new size, then download. If Safe barely helped, try Strong with a lower quality setting.

How to choose the right compression level

Email gateways and upload forms still reject oversized PDFs every day. The instinct is to reach for any online compressor, but many of those tools require an upload. If the document includes personal data or unpublished work, keeping the file on your device is the safer default. PDF Master Lab compresses in the browser: Safe mode cleans structure without redrawing pages, and Strong mode trades selectable text for a much smaller image-based PDF when you need aggressive savings.

Start with Safe mode whenever you still need copy-paste, find-in-page or accessibility-friendly text. It strips unused objects and metadata — useful, but limited if the PDF is already optimized or dominated by large embedded images. When Safe mode only saves a few percent, Strong mode is the deliberate next step. You pick image quality and resolution (96, 144 or 200 DPI), optionally convert to grayscale, and accept that pages become pictures rather than live text.

There is no universal “best” setting. A résumé headed to a job portal may only need Safe mode. A 40MB scan for a quick review can use Strong mode at screen DPI. A handout you will print later deserves Balanced or Print resolution. Compare the reported sizes before you overwrite anything important, and keep the original until you confirm the compressed file opens cleanly on your target device.

Frequently asked questions

What is Safe mode versus Strong mode?
Safe mode is lossless for page content: it removes unused objects and metadata while keeping text selectable and searchable. Strong mode rasterizes each page as a JPEG image, which usually shrinks far more, but text can no longer be selected or searched afterward.
Will compression ruin print quality?
Safe mode does not redraw pages, so visual quality of existing content stays the same. Strong mode depends on the quality and DPI you choose. Screen (96 DPI) suits on-screen reading; Balanced (144 DPI) is a middle ground; Print (200 DPI) keeps more detail for paper.
Why did Safe mode barely reduce my file?
Some PDFs are already lean. If unused objects and metadata are minimal, Safe mode has little to remove. The tool may note that the file was only slightly smaller. Switch to Strong mode when you need a much smaller attachment and can accept image-based pages.
Can I keep form fields when compressing?
In Safe mode you can choose to keep form fields and annotations when that option is available for your file. Strong mode rebuilds pages as images, so interactive form fields are not preserved as fillable fields in the output.
Is compressing here free and private?
Yes. Compression is free with no account. Your PDF is processed locally in the browser and is never uploaded to our servers. We do not store the before or after file. Download the result when you are ready, then close the tab if you want the session cleared.
Does grayscale help file size?
Converting to grayscale in Strong mode can reduce size further for documents that do not need color, such as text-heavy scans or forms. Color charts and photos will lose chroma, so leave color on when hue matters for meaning or branding.

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