Compressor

How Compressor works

Every file you upload moves through the same four-stage pipeline shown above. Nothing is compressed until you tell it to, and nothing leaves your session until you choose to download it.

What gets compressed in each format

“Compression” means something different depending on the file type, because a PDF, a Word document, and a spreadsheet don’t store bloat in the same place. Knowing where the weight actually sits helps you set expectations for how much a given file can realistically shrink.

In every case, the underlying content — your text, formulas, and structure — is left alone. Compression targets the packaging around that content, not the content itself. It’s worth noting that all four formats are, structurally, zipped archives of smaller XML and media files under the hood — which is part of why a document that looks simple on screen can still carry a surprising amount of hidden weight, and why the same compression approach can work across such different file types.

Getting the smallest file without losing what matters

The compression level you choose matters, but a few habits make a bigger difference than any slider setting:

• Match the level to the destination. Use light compression for anything going to print, since print catches quality loss that a screen never will. Save maximum compression for email attachments and internal drafts.
• Flatten before you compress. If your document has stacked layers, tracked changes, or hidden slides, resolve those first — compression shrinks what’s there, it doesn’t clean up clutter for you.
• Batch similar files together. A folder of scanned invoices compresses predictably at one setting; mixing a photo-heavy deck with a plain spreadsheet in the same batch means one of them won’t get the ideal treatment.
• Keep an original copy. Compression is one-way. Once you’ve saved over a source file, you can’t recover the detail that was removed, so archive the original before you compress anything you might need to edit later.
• Recompressing rarely helps. A file that’s already been compressed once won’t shrink much further, and pushing it through maximum compression a second time mostly just degrades quality with little size benefit.

Why file size still matters

It’s tempting to think file size stopped being a real constraint once storage got cheap and connections got faster. In practice, it still shows up constantly: email providers reject attachments over a certain size, client portals and application forms cap uploads at 10 or 25 MB, and shared drives with a whole team’s history in them fill up faster than anyone expects. A slide deck that ballooned to 80 MB because of a handful of uncompressed screenshots is a common, avoidable problem.

Smaller files also move faster in every direction — they upload quicker on a slow hotel Wi-Fi, they open faster for the person receiving them, and they take up less room in backups that your IT team is quietly paying to store. None of that requires giving up quality; it mostly requires removing redundancy that was never doing useful work in the first place, like a photo saved at print resolution inside a document that’s only ever viewed on a screen.

The trade-off is real at the extremes — pushing maximum compression on a file full of detailed photography will show. But for the vast majority of everyday documents, contracts, reports, spreadsheets, slide decks, the difference between the original and the compressed version is invisible to the reader and very visible to your inbox.

There’s also a version-control angle that’s easy to overlook. Large files are the ones people are most tempted to leave out of a shared folder “just this once,” which is exactly how a team ends up with three slightly different copies of the same presentation scattered across email threads. Keeping files small enough to live comfortably in a shared drive, rather than routed around it, is a small habit that prevents a familiar kind of mess later.

Is it safe to compress sensitive documents here?

The short answer is that compression itself doesn’t add risk — it doesn’t read the meaning of your content, only the structure of the file. But it’s still worth being deliberate about where you run any tool that touches a contract, a financial statement, or anything else you wouldn’t want sitting on someone else’s server. Look for three things before you trust a compression tool with a sensitive file: whether it says clearly what happens to your file after processing, whether it needs an account or upload history tied to your identity, and whether it works entirely within your browser session rather than routing files through a third-party queue.

Beyond the tool itself, a good habit is to compress a copy of a sensitive document rather than the only version you have, and to check the result before deleting anything. That way, even if a setting produced a result you didn’t expect, nothing about your process depended on it going right the first time.

Common mistakes people make when compressing files

• Compressing the only copy of a file. Since compression removes data rather than hiding it, working from a copy means a setting you don’t like never costs you the original.
• Using maximum compression by default. It’s tempting to always pick the smallest possible result, but for anything going to print or to a client, the recommended setting almost always looks better for a small difference in size.
• Compressing a file that’s already compressed. Running a JPEG-heavy PDF through compression twice mostly degrades the images further without shrinking the file much more — check the size first before assuming a second pass will help.
• Ignoring what’s actually taking up space. A ten-page Word document with one enormous embedded photo won’t shrink much until that photo is resized or replaced — compression can only do so much with content that’s fundamentally oversized to begin with.

Frequently asked questions