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Mofumi PDF

Compress PDF

Make a PDF smaller for email and upload by re-encoding images and removing dead weight — right in your browser.

100% Private — files never leave your device
Upload PDFDrop files here or click to chooseAccepted: PDF Files never leave your device

About this tool

Most of a PDF's size is usually images: photos from a phone, scans at 600 dpi, or screenshots pasted at full resolution. Compress PDF finds every image, works out how large it is actually drawn on the page, and downsamples anything sharper than the resolution you pick. Photos are re-encoded as JPEG at the quality you choose, while flat graphics such as logos and diagrams are left lossless so their edges stay crisp.

After the images, the tool removes objects that no page uses any more, compresses streams that were stored uncompressed, drops page thumbnails and, if you like, the metadata. Finally the file is repacked with compressed object streams. If nothing we produce is smaller than your original, you get the original back — the result is never larger.

Everything happens on your device. Your document is never uploaded, so confidential contracts, medical records and HR files are safe to compress here.

Engines: pdf-lib · canvas · qpdf

How to use

  1. 1

    Drop the PDF you want to shrink.

  2. 2

    Pick a compression level — Medium suits most documents; use Custom to set the image resolution and JPEG quality yourself.

  3. 3

    Click Compress PDF and download the smaller file. The result card shows how much space you saved.

Use cases

  • Email attachments

    Get a scanned contract or photo-heavy report under the 10–25 MB limit of most mail services.

  • Online forms and portals

    Government and university portals often cap uploads at 2–5 MB. High compression gets most scans there.

  • Archiving

    Shrink large document collections before backing them up, with Low compression to keep quality close to the original.

Frequently asked questions

Will compression make my text blurry?

No. Text and vector drawings are kept as they are; only images are re-encoded. Text stays sharp and searchable at any level.

Which level should I choose?

Low keeps images at about 220 dpi and high JPEG quality — barely visible changes. Medium (150 dpi) is right for reading on screen and office printing. High (100 dpi) gives the smallest file and is fine for screen viewing.

Why did my file barely shrink?

Files that are mostly text, or that were already optimised, have little to remove. Compression can't shrink fonts or vector art much. If the original is already the smallest version, we keep it unchanged.

Is my file uploaded anywhere?

No. The whole process runs in your browser with JavaScript and WebAssembly. Nothing leaves your computer.

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