To compress a PDF for email, open it in a browser-based compressor, choose a compression level, and download the smaller file — the tool shows the before and after size first. It works by re-rendering each page at an optimised resolution and rebuilding the PDF, which shrinks image-heavy and scanned files the most. It runs on your device, so the PDF is never uploaded, with no sign-up and no watermark.
Email and upload forms often cap attachments at 10, 20, or 25 MB, and a scanned PDF can blow past that easily. Compression shrinks the file so it fits. Here is how in-browser compression works, what it trades away, and how to keep control of the result.
This kind of compressor re-renders each page at a lower resolution and image quality, then rebuilds the PDF around those optimised pages. That is what shrinks the file — and it means the output is image-based, so its text is no longer selectable or searchable. It is ideal for scanned documents and image-heavy files you need under a size limit; an already-small text PDF may not shrink much, and a good tool tells you when that happens.
Related tools:
Because this compressor rasterises pages, the result is not searchable text. If you need to shrink a file but keep a real text layer, compress the images another way or, for a scan, run OCR on the compressed result to add a searchable layer back. Everything runs on your device, so very large or high-page-count files are limited by memory, not an upload queue, and a password-protected PDF must be unlocked first.