Originally published on munchymatess.app.
To compress a PDF on Mac without uploading it, click your Munchy Mates pet with two fingers, pick Compress PDF and drop the file on them. You get a new, smaller copy on your Desktop or in Downloads, and your original stays as it was. If the file can't get any smaller, your pet tells you and saves nothing.
That last part matters more than it sounds. We tested the compression filter that comes with macOS, and when we ran it on a file that had already been compressed, the result got bigger. In our test, a second run made a PDF more than five times larger.
What's the best way to compress a PDF on a Mac?
It depends on how often you do it and how private the file is:
| Way | Cost | Uploaded? | The catch |
|---|---|---|---|
| Munchy Mates | $5 for the first 100 users | No | It uses the same macOS filter as Preview, so it won't squeeze harder than Preview can. Apple silicon Macs with macOS 14 or later. |
| Preview | Comes with your Mac | No | Several steps through menus each time, and you have to compare the file sizes yourself. |
| An online compressor | Depends on the site | Yes | Your tax form or ID scan goes to a stranger's server, and you need a connection. |
How do I compress a PDF with Munchy Mates?
- Click your pet with two fingers (or right-click). Five PDF tools circle around them.
- Pick Compress PDF.
- Choose the file in Finder, or drop it on your pet.
- Wait for the "Ta-da!" that tells you where your smaller copy is.
If there's nothing left to squeeze, you'll hear about it. Yuki says, "It's already as small as I can make it, nya!" Then you know right away, and you don't end up with a second file that's no use to you.
How much smaller does a PDF get?
It depends on how much of the file is big pictures. Here's what happened when we ran the macOS filter on four test files we made ourselves:
| Test PDF | Before | After |
|---|---|---|
| 10 A4 pages, each one a large picture, like a scan | 44.9 MB | 4.3 MB |
| 20 pages of plain text | 59 KB | 56 KB |
| 10 large pages whose pictures were already low in detail for their page size | 6.6 MB | 6.5 MB |
| The 4.3 MB scan, compressed a second time | 4.3 MB | 23.5 MB |
A few test files can't tell you what yours will do, and we ran the filter through Apple's PDF tools in a small script. Treat these as a guide. The pattern is still useful: scans and photo-heavy PDFs shrink a lot, and a PDF that's mostly text has little to give.
Why did my PDF get bigger after I compressed it?
Our second run went from 4.3 MB to 23.5 MB. The first run had stored the pictures as JPEGs. After the second run, the file's image data was no longer marked as JPEG, and it took up far more room. We can't say exactly why the filter does this, only that it happened.
So Munchy Mates compares the sizes for you. If the new file isn't smaller, it doesn't save it, and you can't end up with the bigger-file surprise.
Will compressing make my PDF look worse?
It can. The filter changes the pictures inside the PDF. On the Mac we tested (macOS 27.0.1), it asks for pictures at 144 dots per inch, no more than 2,400 pixels on a side, saved as JPEG at 0.7 quality. Apple warns that a compressed PDF may be lower quality too. That's sharp enough for reading on a screen, but it can look soft in print, so check photos and small print before you send the file. Your pet leaves your original alone, so you can always go back to it.
What if the PDF still isn't small enough?
Send only the pages they asked for. Split PDF is in the same ring, and it lets you pick the pages to keep. If you need to put them back together with other files, Merge PDFs is right next to it.
Do I need to upload my PDF to compress it?
No. Munchy Mates does the work on your Mac, and after you activate your license key once, the PDF tools work offline.
Why a pet, though?
Because PDF chores are more fun with a friend on your screen. You pick a cat, a pup or a bunny and give them a name. They react to what your Mac is doing: hungry when your battery hits 20%, crying at 10%, asleep from 1 to 8 am. They also eat the files you drag to them, which go to the Trash so you can put them back. Five PDF tools come with them.
Got a PDF that's too big to send? Play with the live demo on our site, then adopt your own pet for $5.
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I'm the solo developer behind Munchy Mates, a native Swift/AppKit desktop pet for Apple silicon Macs. Questions about building it are welcome in the comments.
