Reduce PDF file size in seconds so large documents fit email limits and upload portals. Completely free, with no watermark and no signup. This browser-based PDF compressor shrinks your file on your own device, so it is never uploaded to a server.
Quick answer: To compress a PDF means to reduce its file size by re-encoding the images and page data inside the document, so it takes up less storage and uploads faster. You pick a compression level, the tool re-renders the pages at a smaller size, and you download a lighter PDF.
This works best on scanned and image-heavy PDFs, which often shrink by half or more. A PDF that is already mostly text may not shrink at all, and the tool tells you when that happens rather than handing you a bigger file.
📦 Compress PDF
Your file is processed on this device and is not uploaded to any server.
Drop your PDF here
or click to browse. One PDF file at a time.
Working...
Compressed
0% smaller
This compressor re-renders each page as an optimised image, which is what shrinks scanned and image-heavy PDFs so effectively. Selectable text becomes part of the page image, so keep a copy of the original if you need to edit or search the text later.
Click the box above or drag a file onto it. The tool reads the document and shows its current size and page count before you do anything.
Balanced at Standard resolution suits most documents. Drop the resolution to Screen for the biggest savings, or tick grayscale for scanned text.
You get the original size, the new size, and the exact percentage saved. If the file would end up larger, the tool says so and offers the original instead.
Many PDF compression websites upload your document to a server, optimise it remotely, and send back a smaller copy. This tool keeps your file on your device instead.
It renders each page with PDF.js, the PDF engine Mozilla built for Firefox, re-encodes each rendered page as a JPEG at your chosen quality and resolution, and rebuilds a new PDF with jsPDF. All of that happens in your browser tab. Nothing is transmitted.
That approach is very effective on scanned documents and PDFs full of photographs, where image data is the reason the file is large. It is much less effective on documents that are mostly text, because text stored as text is already compact. Turning that text into an image can make the file bigger, which is why the tool checks the result before offering it to you.
| Document type | Typical result |
|---|---|
| Scanned pages, photos, brochures | Often 50 to 80% smaller |
| Mixed text and images | Usually 20 to 50% smaller |
| Plain text documents, exported reports | Little change, sometimes larger |
| Already-compressed PDFs | Little to no further saving |
Because the work happens in your browser, the practical ceiling is your device's memory rather than a server limit. Files up to roughly 50 MB or 200 pages are comfortable on a desktop. A phone will manage considerably less. Past that point the tab may slow or stop, and the tool warns you before starting rather than failing halfway.
Two things it does not do: it cannot open a password-protected PDF until the password is removed, and it does not preserve selectable text, since pages become images. If you need the text to stay searchable, this is the wrong tool for that file.
Your file is read and rebuilt in the browser tab. It is not uploaded, so sensitive documents never travel anywhere.
Quality, resolution and colour are three separate controls, so you can tune size against clarity for the document in hand.
The output is clean. No stamps, no forced trial, no email address, and no cap on how many files you compress.
Works on Windows, macOS, Linux, iOS, Android and ChromeOS. Larger files will need a desktop.
When you compress a PDF here, the file is read, re-rendered and rebuilt entirely inside your browser. It is not uploaded to a server, not stored, and no account or email is required. Close the tab and nothing remains.
That covers the file itself. Like most websites, Anchor AI Tools uses analytics and serves fonts and scripts from third-party providers, which is covered in our privacy policy. We mention this because "private" should mean something specific: your document stays on your machine.
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PDF Editor
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JPG to PDF
Turn images into a single PDF document.
PDF to JPG
Export every page as an image file.
Compression behaviour on this page is described from how the tool actually works, including the cases where it does not help · How we check our tools
Compression re-encodes page imagery. Keep your original file if you need editable text or full print resolution.
Written by Amara Taylor for Anchor AI Tools · Last reviewed September 13, 2026 · © 2026 Anchor AI Tools