Compress PDF
Shrink a PDF's file size right in your browser — recompress its photos while keeping text selectable, optimise its structure losslessly, or flatten pages for maximum savings.
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Drop a PDF here, or click to choose one
Compression mode
Result
Original — page 1
Compressed — page 1
How to compress a PDF
- Choose a PDF.
- Pick a mode: Compress images, keep text suits most files, Optimise structure is lossless, and Flatten pages to images is strongest, for scans.
- Click Compress PDF, compare the before and after preview and sizes, then click Download compressed PDF.
About this tool
Most of a PDF's file size comes from embedded photos and internal bloat (uncompressed object tables, duplicated resources, editor metadata). This tool offers three honest strategies rather than a magic "compress" button that quietly does one of them:
Compress images, keep text is what professional tools such as Acrobat's "Reduce file size" and Ghostscript do. It finds each photo embedded in the PDF, scales it down so it's no sharper than your chosen resolution needs for a full page, and re-encodes it with MozJPEG — in greyscale if it has no colour. Everything else is left exactly as it was: text stays selectable and searchable, and fonts, vector drawings, links, bookmarks and form fields are untouched. An image is only replaced if the new version is at least 10% smaller, and ones that could be damaged by JPEG compression are left alone — transparency masks, logos and diagrams with flat colours, and CMYK or indexed-colour images.
Optimise structure rebuilds the file's internal object streams and cross-reference tables in their most compact form without touching a single pixel or character. It's lossless, and savings depend on how much internal bloat the file had — a PDF exported by an efficient tool may shrink very little.
Flatten pages to images renders every page to a JPEG and assembles a new PDF from them. Text is then no longer selectable, searchable or copyable, and fine text can look soft at low resolution — but it's the strongest option for scans and stubborn files, and black-and-white pages are stored in greyscale, which roughly halves them.
Every mode shows a before/after preview of page 1 and the exact size change, and tells you plainly if a file barely shrinks. Everything happens locally in your browser with pdf.js, pdf-lib and WebAssembly image codecs; your PDF is never uploaded anywhere.
Questions about compressing PDFs
Is it really free?
Yes. There’s no account, no signup, no trial and no paid tier, and the file you download has no watermark. It has no ads either: toolcrate keeps its PDF and file tools ad-free.
Are my files uploaded anywhere?
No. The PDF is opened and processed by your own browser, on your own device, and is never sent to a server. That makes it safe for contracts, bank statements, medical letters and anything else confidential.
How much smaller will my PDF get?
It depends on what’s inside. PDFs full of photos or scanned pages shrink the most; files that are mostly text are usually small already. The tool shows the exact size change and says plainly if a file barely shrinks.
Will the text still be selectable?
Yes, with Compress images, keep text and with Optimise structure: only the photos change. Flatten pages to images turns each page into a picture, so its text can no longer be selected or searched.
How do I make a PDF small enough to email or upload to a form?
Use Compress images, keep text and lower the image resolution, for example to 96 or 72 DPI. For scanned documents, Flatten pages to images usually gives the smallest file.
Does it work on a phone?
Yes. It works in the browser on iPhone, Android, tablets and computers, with no app to install. Once you’ve used it, it keeps working without an internet connection.