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Optimize PDF Online Free

Drop a PDF, pick a style, click once — fast, clear, and private. Nothing is uploaded.

This tool reduces PDF file size in your browser by re-encoding the images inside the document at a lower quality, which is where almost all the weight in a scanned or image-heavy PDF sits. Text-only PDFs are already compact and will shrink very little. Nothing is uploaded to a server.

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About this tool

This is a PDF Optimizer, not a heavy re-encoding pipeline. After you add a file (up to 25 MB), you see only the name and size. When you click Optimize PDF, pdf-lib runs exactly one save pass in your browser: Fast Compression (recommended) for the lightest work, Email Friendly to strip metadata, and Reduce More to also use PDF object streams.

There are no trial passes, no target-size loops, and no page rasterization — so text stays selectable and the page stays responsive. When finished you see a size comparison, a download button, and the option to optimize another file. Your file never leaves your device.

How to use

1

Upload your PDF

Drop your PDF into the upload area or click to browse. Maximum file size is 25 MB.

2

Choose a preset

Select Fast Compression for a quick pass, Email Friendly to clean metadata, or Reduce More for the smallest output.

3

Optimize

Click Optimize PDF and wait for the spinner. The tool runs one pdf-lib pass — no loops, no rasterization.

4

Download or optimize another

See the before/after size comparison, download your optimized PDF, or click Optimize another file to start again.

At a glance

Maximum file size
25 MB
How it compresses
Re-encodes the images embedded in the PDF at a lower quality and resolution
Presets
Smart (balanced), Email (~500 KB target), Maximum reduction, Custom target size, and High quality (minimal compression)
Default rendering
150 DPI on the Smart preset
What will not shrink
Text-only PDFs. Their weight is glyph data, not images, so there is little for image compression to remove
Privacy
Compression runs in your browser; the document is not uploaded

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Compress the source images before converting to PDF for smaller outputs.

Image to JPG

Convert to JPG first for smaller embedded images in your PDFs.

Frequently asked questions

Answers about optimizing PDFs locally, the three presets, the 25 MB limit, and privacy.

Last updated

Yes. Everything runs in your browser with pdf-lib. Your file is not uploaded to our servers — it stays on your device until you download the result.

All three use a single quick save pass. Fast Compression (recommended) is the lightest. Email Friendly also clears common document metadata. Reduce More adds PDF object streams when saving, which can reduce size further on many files — still one pass, no heavy loops.

Many PDFs are already compact. This tool avoids slow full re-rendering, so savings come from structure and metadata — some files change very little.

No. After each pass we compare sizes. If the new file would be the same size or larger, we keep your original bytes for download and tell you clearly — we never pretend a bigger file is smaller.

It keeps the experience fast and reliable in the browser. For larger documents, split or optimize them in desktop software first.

Yes. Pages are not flattened into images, so text that was selectable before should stay selectable.

Encrypted PDFs cannot be opened here. Remove the password in another app, then optimize the file in this tool.

Rarely, a complex PDF may hit the safety timeout. Try again, use Fast Compression, or use a smaller file under 25 MB.